Nogales, Sonora, lies just south of the United States–Mexico border, in a city divided by a fence. Its significance in the book rests on the contrast with its northern counterpart: two neighboring communities with similar geography and shared cultural roots experience markedly different incomes, public services, security, and political accountability. The border makes visible how institutions, shaped by divergent histories, distribute opportunity and public authority.

A divided city

The difference appears in ordinary measures of life. The average household income in Nogales, Sonora, is about one-third of that in Nogales, Arizona. Most adults south of the fence have not completed high school, and many teenagers are not in school. Infant mortality is high, public-health conditions are poor, and residents do not live as long as their northern neighbors. Roads are in bad condition, crime is high, and opening a business carries risks: would-be business owners must contend not only with robbery but also with the difficulty of obtaining permissions and the expectation of paying bribes.

These are not simply differences in private wealth. Public amenities and government performance shape daily security and economic life. Residents of Nogales, Sonora, live with political corruption and ineptitude; businesses operate amid uncertainty about both personal safety and the security of their investments. Health disparities, too, are connected not to different disease environments but to inferior sanitary conditions and inadequate health care south of the border.

Political experience also diverges. Democracy is a recent experience in Nogales, Sonora. Until Mexico’s political reforms of 2000, the city, like the rest of the country, was under the corrupt control of the Institutional Revolutionary Party. The contrast with the United States side is therefore not only between different levels of income or public provision, but between different relationships to political power and accountability.

Common ground, different institutions

The border does not separate two populations with fundamentally different environmental or cultural origins. The cities share a climate, geography, and local disease environment; germs cross the border without restriction. Nor does the contrast rest on a simple division between European-descended residents in the north and Indigenous-descended residents in the south. The inhabitants have broadly similar backgrounds, share ancestors, and enjoy the same food and music.

The history of the region underscores that common ground. After Mexico became independent from Spain in 1821, the area around Los dos Nogales was part of the Mexican state of Vieja California. It remained so after the Mexican-American War of 1846–1848. Only with the Gadsden Purchase of 1853 did the United States border extend into the area. A surveyor, Lieutenant N. Michler, noted the valley of Los Nogales; settlements then developed on either side of the border. The later division of the city thus imposed an institutional boundary across a place whose residents were not separated by a comparable gulf in ancestry or culture.

The border places the two halves under different systems. Nogales, Arizona, is within the United States and its economic institutions, which allow people to choose occupations, acquire education and skills, and work for employers encouraged to invest in better technology. These conditions support higher wages. Political institutions give residents a role in choosing representatives and replacing them when they misbehave; in response, politicians have incentives to provide services that citizens demand, from public health and roads to law and order.

Nogales, Sonora, is shaped by different institutions and the incentives they create for residents, entrepreneurs, and businesses. Its residents face a riskier environment for investment and a weaker provision of public services. The comparison identifies institutional differences, rather than geography or inherited cultural character, as the main reason for the unequal prosperity of the neighboring cities.

The longer history behind the border

The book places this local contrast within a wider account of institutional divergence. Differences that may initially seem small can become consequential as economic opportunities expand. In the seventeenth century, Atlantic trade and colonization created wealthy groups of traders in England who had relatively few ties to the Crown. They resented royal control and pressed for political changes and limits on royal prerogatives, playing important roles in the English Civil War and the Glorious Revolution. In Spain and France, monarchs were better able to monopolize trade, leaving opponents of absolutism less numerous and less powerful. This comparison presents institutional development as a historical process, not an automatic consequence of geography or culture.

The account also follows the other side of European commercial expansion: colonial power often strengthened or imposed extractive institutions elsewhere. In the Moluccas, the Dutch East India Company used its military power to suppress competitors and secure control of the spice trade. After establishing a monopoly on cloves in Ambon, it expanded its efforts across the northern Moluccas, imposed restrictions on clove cultivation and trade, and intensified existing tribute and forced-labor systems. The book emphasizes that European expansion could foster institutional change in one place while destroying commercial prospects and autonomy in another.

That broader history supplies context for the contrast at Nogales, without reducing the city to a single colonial episode. The argument is that economic development depends on institutions that create incentives and on political arrangements capable of supplying order and public goods. European commercial expansion could contribute to prosperity where it supported more inclusive institutions, but it could also reinforce extractive arrangements that prevented local societies from benefiting from new technologies and economic change.

What the comparison shows

Nogales, Sonora, is presented not as an isolated case but as one half of a controlled comparison. The nearby border separates communities that share climate, local conditions, and cultural ties, yet live under different national institutions. The contrast makes the consequences of those arrangements legible in household income, schooling, health, public infrastructure, business risk, and political accountability.

The city’s place in the argument is therefore both concrete and explanatory. Its roads, schools, health conditions, and business environment are not treated as disconnected indicators; together they show how institutions structure residents’ opportunities and the state’s responsiveness. The account then turns from the visible line between the Nogaleses to the historical paths that produced institutional differences, setting up a wider inquiry into how colonial foundations and later political development shaped prosperity and poverty.