Environmental Degradation in a Dependent Region: The Rio Grande Valley of Mexico and Texas


Richard C. Jones

The emerging global company is divorced from where it produces its goods. It has no heart and it has no soul. It is a financial enterprise designed to maximize its profits.

—Robert B. Reich1


A nostalgic outpost of the “Wild West,” the Texas-Mexico border is also the frontier between a Third World and a First World country. Mexico’s historic dependence on (and conquest by) the United States has created an unequal economic relationship whose most recent expression is the transit of prodigious quantities of people and goods across this “fragile frontier.” The Texas-Mexico border is a steppe and desert region with poor capacity to sustain human occupation. It is not surprising that the region has become an environmental sink for the byproducts of these people and goods. It is somewhat startling, however, that as the environment has degraded, diseases such as hepatitis, cholera, and birth defects have emerged.

This article traces the interrelationships among dependence, environmental degradation, and human health in the Rio Grande Valley of Mexico and Texas. It also presents results of a study of environmental factors impinging on family health in households located on both sides of the border.


Mexico’s Historical Dependency

Mexico’s dependence on the United States exemplifies the classic tenets of dependency theory, which examines the unequal economic relationship between rich and poor countries.2 Dependency theorists divide the countries of the world into two groups with different kinds of economies and different prospects: the core and the periphery. The core group consists of advanced industrial countries with abundant capital to invest, diversified economies, a strong manufacturing base, and advanced technology. Countries in the periphery have the opposite characteristics: a lack of local capital, heavy dependence on the export of a limited number of products (often crops or minerals), and weak indigenous manufacturing industries and technological development.

Countries in the periphery are dependent on core countries for investment capital and advanced manufactured products. Because of the weak and fluctuating value of their exports, combined with the need to import manufactured goods from core countries, their currencies are typically weak against major world currencies such as the dollar. The devaluations of the Mexican peso have been an example of this trend.

Relations between core and peripheral countries can lead to rapid economic growth in peripheral nations, but the benefits of this growth are distributed unequally between different localities and economic classes. In peripheral countries, the rich often own a huge share of property, and become richer by profiting from the economic connections between their own countries and core countries (e.g., by serving as agents or local executives for multinational corporations, or by benefiting from their countries’ exports of commodities).

The situation of the poor in a peripheral country is one of extreme deprivation. In the urban slums and rural hinterlands, poverty is endemic and populations are cut off from the adequate income, consumer lifestyle, education, and health enjoyed by the elites and middle class. Living in overcrowded, unhygienic conditions without independent means of survival, the fate of the poor is to serve as cheap labor wherever they can find employment.

The economic history of Mexico has exemplified the problems that dependency theorists consider will beset a poor country living in the shadow of an economically powerful neighbor. The Porfiriato—the rule of Mexican dictator Porfirio Diaz (1877-1910)—was a decisive period establishing the framework of the twentieth-century economic relationship between Mexico and the United States. The Mexican government under Diaz encouraged foreign investment in mining, agriculture, and infrastructure, particularly in the north of Mexico. This foreign investment reached such levels that a writer of the time described Mexico as “the mother of foreigners and the stepmother of Mexicans.”3

Since then, the development of Mexico has been closely tied to its relationship with the United States. For example, a “Mexican economic miracle” (6% annual growth of GNP, 1940-70) is popularly assumed to have been the result of nationalistic policies aimed at replacing imported products with Mexican manufactures that began with President Lazaro Cardenas (1934-40). But it was also dependent on the import of consumer goods manufactured for the Mexican market by U.S. firms, and on Mexican exports of oil, winter vegetables, and tourism.4

Historically, Mexico has depended heavily on exports to the United States that have a number of competitive disadvantages. Both cotton (until 1975) and petroleum (until the mid-1980s) were vulnerable to substitution by the same commodities offered by other countries, and were beset by widely fluctuating world prices for these commodities. In fact, the brief oil boom of 1978-82, described by one commentator as a “veritable fiesta of borrowing and spending” accompanied by government inefficiency and corruption,5 ended in disaster. With the decline in oil prices in 1982, Mexico found itself bankrupt, facing its worst depression since the Mexican Revolution. From the ashes of this depression emerged policies such as peso devaluation, government divestment, and trade liberalization, which by the late 1980s had reversed the decline and encouraged foreign investment in Mexico once again.

U.S. investments in Mexico surged during the 1980s and 1990s, targeting export manufacturing, services, and the Mexican stock market.6 Mexican border states are attractive to retail franchises and banking (as in Monterrey and Nuevo Leon), joint-venture commercial agriculture (as in southern Tamaulipas), and export-oriented assembly plants, or maquiladoras, located largely in cities along the border as encouraged by the Mexican Border Industrialization Program that began in 1965. Although Mexico’s economic statistics indicate a recent shift to manufactured goods (82% of exports in 1996), this largely involves maquiladora plants that are controlled by U.S. corporations and accorded special privileges in Mexico. More than 70% of these plants are situated in Mexican border municipios (counties). Moreover, in a perfect example of economic asymmetry, 84% of Mexico’s exports and 76% of her imports in 1996 were to or from the United States, while only 9% of the United States’ comparable trade was with Mexico.7

The new relationship is having profound effects on Mexican society. The Mexican businessmen who are economically dominant in the maquiladora localities, though dependent on U.S. entrepreneurs, are flourishing. Franchised stores such as Walmart or McDonald’s, which are dependent on U.S. corporate decisions, simultaneously dominate local markets and displace local storeowners.8 Successful migrant workers who have lived in the United States and done well economically can, based on their wealth, assume economic and social leadership in their villages of origin.9 Many migrant workers, however, lead a harsh existence, performing backbreaking labor at low wages and living in dismally overcrowded and unhygienic conditions.


Rapid Growth in the Border Region

The cities that straddle the Rio Grande River from El Paso/Juarez to Brownsville/Matamoros (see map) have historically been a physical and economic backwater. The Coahuiltecan Indians who inhabited the region at the time of European contact were nomadic gatherers compelled to forage food from the unforgiving landscape. The Spanish avoided the region as much as possible.10

An interlude of agricultural expansion near El Paso and Brownsville around the turn of the last century was followed by stagnation in subsequent decades, as growth surged in other parts of Texas.11 To illustrate, as recently as the 1960s, when Texas’ overall population grew 17% and that of metropolitan areas 24%, border metropolitan areas grew as follows: Brownsville, -7.1%; McAllen, 0.3%; Laredo, 12.5%; and El Paso, 14.4%.12

After the peso devaluation that followed the 1980s oil crash, U.S. border cities were hard hit. Their retail sectors shriveled as Mexican consumers became unable to afford U.S. goods. Soon thereafter, the cheap labor of Mexican workers became a super-bargain for U.S. maquiladoras, which located in the Rio Grande Valley with renewed vigor, aided by a more open Mexican
government stance. Trade flowed through U.S. cities such as El Paso, Laredo, and Eagle Pass, while the Lower Rio Grande Valley became very attractive to “Winter Texans.”

The entire Rio Grande Valley pulsated with new economic life. Between 1980 and 1990, the Texas population grew by 19%, and the average population for metropolitan areas by 23%; but the rates were 24% for Brownsville, 35% for McAllen, 34% for Laredo, and 23% for El Paso.13 On the Mexican side of the border, population growth rates in the Rio Grande Valley cities were also higher than rates for their encompassing border states. Rio Grande Valley maquiladoras displayed even more phenomenal growth—augmenting their number of employees from 2.5 to 6.5 times their 1980 levels.14

As dependency theory suggests, economic growth is not the same as economic development. During the 1980s, the median income of Texas families living in the four above-mentioned Rio Grande Valley metropolitan areas declined from 70% to 66% of the state average. Whereas the overall state economy matured, moving away from manufacturing toward the higher order services, the Rio Grande Valley economies did the reverse.15 And growth in the Valley came at a high environmental cost.


Environmental Degradation

Maquiladoras are the hub of environmental problems in the Rio Grande Valley. They locate across the Mexican border not only for the lower labor costs there, but because environmental enforcement in Mexico is lax compared to that in the United States. Even at wages of less than $10 per day (the current rate), maquiladoras do not suffer a shortage of job applicants, some two-thirds of whom are female. Many come from interior Mexican states, where casual wages are $5 per day or less. They arrive daily in cities such as Matamoros, Piedras Negras, and Acuna, from states such as Durango, Zacatecas, Guanajuato, and San Luis Potosi.16

The new workers move into makeshift housing in colonias (neighborhoods) without plumbing or drainage, next to arroyos (creeks) that flow into the Rio Grande. When it rains, their sewage is flushed into the river—the same river that is the water supply for all the binational Rio Grande Valley cities except Del Rio, which relies on the San Felipe springs.

Recent research shows that the new maquiladoras are more polluting than their predecessors of the mid-1960s. The early plants were textile operations using few chemicals. The current plants are disproportionately represented by the electronics and auto parts industries, which use a witches’ brew of toxic cleaning, plating, and soldering agents, as well as plastics and leather.17 Mexican law requires that all hazardous maquila wastes be returned to the United States (or other countries of origin), but only a fraction are actually sent back.18 Toxic wastes from these processes often end up in local surface and ground waters.

Maquiladoras are suspected of dumping wastes into local sewers and streams, sending them to unauthorized dump sites where waste percolates into the groundwater, and selling them to Mexican recyclers, in which case they may eventually enter groundwater and surface water.19 Maquilas have also directly exposed workers to hazardous chemicals—as in the case of the U.S.-owned Mallory capacitator plant in Matamoros in the late 1970s, where pregnant women were exposed to PCBs resulting in as many as thirty babies being born mentally retarded.20

Human Health

Many infectious and prenatal diseases affect Rio Grande Valley residents at higher rates than those elsewhere in Texas or the United States. Hepatitis A (infectious hepatitis), a viral disease of the liver, is twice as prevalent in the Texas Rio Grande Valley as in Texas overall. In the Middle Rio Grande Valley from Del Rio to south of Laredo, it is more than five times as prevalent. Bacterial water-borne gastrointestinal diseases, such as salmonellosis and shigellosis, in the Texas Rio Grande Valley are 50% above state averages, and are more than twice the averages of the state in the Middle Rio Grande Valley.21

Although records are more sketchy for Mexico, data available for border states indicate rates of hepatitis A twice those of the Texas border counties, and rates of gastrointestinal diseases ten times as high.22 More startling is the increase in neural tube disorders—particularly anencephaly—in the Rio Grande Valley region since 1990. Anencephaly, an affliction in which the fetus is born with an open neural tube and the absence of most of the brain as well as the crown, is 100% fatal.23 It became a nationwide concern when the Texas Department of Health found that rates in Brownsville were four times the national average.24 Even higher rates were later uncovered for Del Rio.25 The causes of anencephaly are still speculative, but environmental toxins affecting either the mother or the father are a prime suspect, along with diet and genetics.

The Middle Rio Grande Valley is apparently a newfound mecca for both maquiladoras and infectious diseases. The combination of low wage rates and the absence of labor activism and environmental enforcement has activated a spatial diffusion of maquiladoras from the upper and lower Rio Grande areas into the economic and environmental “vacuum” in between. Both environmental pollution and disease have diffused into this same vacuum, as demonstrated by the later dates of newspaper articles on environmental and health concerns in the Middle Rio Grande Valley as opposed to the other two regions.


Case Study: Results of a Household Survey in the Middle Rio Grande Valley

Despite the apparent spatial and temporal relationships between environment and health, surprisingly few scientific studies have attempted to link exposure to pollution and disease at the household level. Those that have been conducted focus narrowly on household sanitation, to the neglect of the geographic location of the household and the external behavior of household members.

An Environmental Protection Agency (EPA) grant in 1996 enabled this author, assisted by a team of research associates at the Hispanic Research Center at the University of Texas at San Antonio, to conduct a study aimed at bridging this gap in the medical literature. We investigated the correspondence between specific diseases (gastrointestinal, respiratory, nervous or congenital) and a wide range of environmental site and situation factors. Our subjects were 2,140 households in the three binational cities of the Middle Rio Grande Valley region: Laredo/Nuevo Laredo, Eagle Pass/Piedras Negras, and Del Rio/Ciudad Acuna.

The target households were chosen randomly from neighborhoods characterized by substandard housing and their location near three potential sources of environmental stress: polluted streams, industries, or agriculture. It was hypothesized that households situated closest to such sites would exhibit a greater incidence of specific diseases, depending on a number of variables. These variables included lower socioeconomic status, lack of water/drainage, and household member contact with pollutants as a result of acts of circulation (work, visitation, and migration).

The relationships uncovered by the study are persuasive. The results presented here are for the incidence of gastrointestinal disease, as shown in Table 1. In the Mexican cities, proximity to polluted watercourses and agriculture—which are common features of the unregulated land use mixtures found in these cities—is strongly associated with gastrointestinal ailments (see the first three data columns of Table 1). Specifically, 29.6% of households defined as close to agriculture showed the ailment, compared with only 12.6% of households defined as far from it. The comparable disease rates for households close to as opposed to far from streams were 18.6% and 12.5%.

The high correlation between living in agricultural areas and gastrointestinal disease can be explained by a number of factors. Maquila workers often settle in colonias on the urban periphery and practice agriculture to supplement their income. In fact, an urban-oriented agriculture has developed on the urban periphery, consisting of feedlots, dairies, and truck gardening. In view of the problems arising from the location of maquilidoras, some might expect the relationship between a household’s living in proximity to industry and experiencing gastrointestinal disease to be higher. However, the kind of diseases linked to industrial pollutants tend to be connected to neurological disorders and cancers rather than with gastrointestinal diseases. In results not detailed here, we found that in Mexico, proximity to an industrial area was more associated with such diseases as neurological disorders and cancers than was proximity to agriculture, standing water, or streams.

In addition to proximity factors, households with five or more members, or with a member/members experiencing toxic exposure on the job, showed a higher incidence of gastrointestinal disease. (In the latter case, workers in various food processing, tanning, agricultural, and food-handling jobs may have brought biological contaminants into their homes.)

In the U.S. cities, a wide array of factors are important in the incidence of gastrointestinal diseases. The three most salient are family size, the frequency with which a family crosses the border into Mexico, and proximity to stagnant water (the last three data columns of Table 1).

When several risk factors are combined, exceedingly high levels of gastrointestinal diseases are found. On the Mexican side, almost half (48%) of large families who lived near agriculture or streams, and who had a member working with toxic materials on the job, had some form of the disease, compared to only 16% of all the Mexican families surveyed. On the U.S. side, 28% of large families living near stagnant water who visited Mexico frequently had the disease, versus only 15% of all U.S. families in the survey.



The problems faced by inhabitants of the Rio Grande border region are more commonly seen in the Third World than in industrialized nations. They include rapid economic growth injected by external forces, a continuation (or worsening) of poverty, and a deterioration of the environment and human health. As shown here, the Rio Grande Valley region cannot escape the unequal dependent relationship that marked U.S.-Mexican affairs for 150 years. Mexico’s economic subordination to the United States, coupled with its economic collapse during the 1980s, led to its embracing free trade at any cost—and the environmental and health costs have been high for the border region.

This case study suggests that spatial location and human behaviors are of paramount importance in determining which families are exposed to pollution and subsequently contract infectious diseases. To counteract this problem, the immediate need on the Mexican side of the border appears to be for more restrictive zoning (and industrial relocation), so that homes are not situated next to polluting industries, agriculture, or sewage-laden streams. On the U.S. side, more accessible public health services and better drainage appear to be the top priorities.

The maquiladora industry needs to pay for the negative effects it creates for border society, and to begin to provide the housing, infrastructure, and pollution mitigation needed for the workers on whom its huge profits ultimately depend. Until it is compelled to do so, the causal chain will not be truly broken.



1. Robert B. Reich, quoted in Sandy Tolan, “Shantytowns Are Part of Mexican Border Boom,” San Antonio Light (August 19, 1990) (excerpted from The New York Times Magazine).

2. H. A. Reitsma and J. M. G. Kleinpenning, The Third World in Perspective (Totowa, N.J.: Rowman and Allanheld, 1985), 244-264.

3. Cited in Alan Riding, Distant Neighbors (New York: Vintage Books, 1985), 40.

4. Ibid.: 136-140.

5. Ibid.: 145.

6. Tom Barry, ed., Mexico: A Country Guide (Albuquerque, N.M.: The Inter-Hemispheric Education Resource Center, 1992), 303-312.

7. Encyclopedia Britannica 1997 Book of the Year (Chicago: Encyclopedia Britannica, Inc., 1998).

8. Barry, 310-311.

9. Joshua Reichert, “The Migrant Syndrome: Seasonal U.S. Labor Migration and Rural Development in Central Mexico,” Human Organization 40 (1981): 56-66; Richard C. Jones, Ambivalent Journey: U.S. Migration and Economic Mobility in North-Central Mexico (Tucson: University of Arizona Press, 1995), 81-84.

10. W. W. Newcomb, Jr., The Indians of Texas: from Prehistoric to Modern Times (Austin: University of Texas Press, 1961), 30-57; Donald W. Meinig, Imperial Texas: An Interpretative Essay in Cultural Geography (Austin: University of Texas Press, 1969), 23-28.

11. Meinig, 98-102; Terry G. Jordan, John L. Bean, Jr., and William M. Holmes, Texas: A Geography (Boulder: Westview Press, 1984), 177-79.

12. U.S. Bureau of the Census, Census of Population and Housing 1970.

13. U.S. Bureau of the Census, Census of Population and Housing 1990.

14. Instituto Nacional de Estadistica e Informatica, Mexico. 1990. XI Censo de Poblacion.

15. U. S. Bureau of the Census, 1990.

16. Instituto Nacional de Estadistica e Informatica, Mexico, 1990.

17. Miguel Monroy, “Bi-national Management of the Maquiladora Industry: Hazardous Waste on the U.S.-Mexico Border,” Border Health VII (1991): 3-18; Herbert H. Otega and Victoriano Garza, “Evaluation of the Implications of the Impact of Hazardous Waste from the Maquiladora Industry in the U.S. Mexico Border,” Border Health VII (1991): 34-38.

18. Leslie Kochan, The Maquiladora and Toxics: The Hidden Costs of Production South of the Border (AFL-CIO, Publication 186, 1989).

19. Melanie Trevino and Adolfo Fernandez, “The Maquiladora Industry, Adverse Environmental Impact, and Proposed Solutions,” Journal of Borderlands Studies VII (1992): 53-72.

20. Kochan, 10; Victoriano Garza, “Transborder Movement of Toxic Substances and Its Risks for Public Health,” Border Health VIII (1992):1-6.

21. Epidemiology in Texas, Annual Report (Austin: Texas Department of Health, Bureau of Disease Control and Epidemiology, 1991).

22. Linda S. Chan, Roy McCandless, Bernard Portnoy, Chandler Stolp, and David C. Warner, Maternal and Child Health on the U.S.-Mexico Border. Special Project Report (Austin: Lyndon B. Johnson School of Public Affairs, University of Texas at Austin, 1987): 123-142; John W. House, Frontier on the Rio Grande: A Political Geography of Development and Social Deprivation (Oxford: Clarendon Press, 1982), 137.

23. Epidemiology in Texas.

24. Jean D. Brender, Lucina Suarez, and Judy Henry, “Anencephaly in Texas Border Counties, 1986-1991,” Disease Prevention News 53, no. 19 (1993): 1-5; Sandra Garcia, “No One Can Tell the Parents Why,” San Antonio Express-News (June 27, 1992).

25. Brender et al.


Richard C. Jones is a professor of geography in the Division of Social and Policy Sciences at the University of Texas at San Antonio.

Table 1

Relationship between Gastrointestinal Disease and Selected Independent Variables in
Environmentally Strained Colonias in the Middle Rio Grande Valley



Response Ratioa Response Ratioa

Yes No Yes No

Independent Variable (1) (2) (3) (4) (5) (6)

Percent of Households Suffering from Disease:b

Household Utilities:

Lack piped water in household? 11.5 16.0 .70 23.1 15.1 1.53

Lack drainage in household? 16.0 13.6 1.18 17.9 13.9 1.29

Location of Household Relative to Pollution:

Less than 500m from stream? 18.6 12.5 1.49** 17.0 13.7 1.24

Less than 500m from stagnant water? 17.7 14.9 1.19 22.1 14.2 1.56**

Less than 500m from agriculture?c 29.6 12.6 2.35*** 17.3 15.1 1.15

Less than 500m from industrial area?d 16.9 14.3 1.18 14.6 16.2 .90

Household Contacts:

Toxic exposure on job?e 18.6 12.5 1.49** 18.6 12.9 1.44**

Contact with river/stream?f 18.9 14.0 1.35* 17.9 14.6 1.23

Cross border frequently?g 17.5 13.1 1.34* 17.2 10.8 1.59**

Head born elsewhere?h 14.6 21.3 .69 15.3 14.5 1.06

Household Demographic Characteristics:

Is family size 5 or less? 17.9 12.5 1.43** 20.6 12.3 1.67***

Has household head had less than 7 years schooling? 16.9 12.5 1.35 13.6 16.1 .84

Number of households interviewed 823 779


*** Significant at the .01 level. ** Significant at the .05 level. * Significant at the .10 level


a The ratio of “yes” to “no” responses, i.e., column 3 is the ratio of column 1 to column 2; column 6 is the ratio of column 4 to column 5.

b Percentage of households in which a member has (in recent years) suffered from a gastrointestinal disease (chronic diarrhea, and amoeba, intestinal parasite, salmonella, typhoid, liver inflammation [hepatitis], and related disease).

c Includes active agricultural fields or livestock operations.

d Includes areas of manufacturing, mining, repair shops, junkyards, warehouses, construction sites, and related activities.

e Positive response (by or for any household member) to question, “In the place where (household member) works, do they use substances such as paints, soldering, detergents, solvents, insecticides, acids, or other materials, or do they generate dust or strong odors that could be considered harmful?”

f Whether any household members walk, wash, or fish in river or stream.

g Visitation across the border more than once per year.

h In Mexico, refers to born elsewhere in the country (versus locally); in the United States, refers to born abroad.

©1999 National Council for the Social Studies. All rights reserved.