Nogales, Arizona, is the northern half of a city divided by the United States–Mexico border. Its contrast with Nogales, Sonora, only a few feet away, gives the book a vivid demonstration of how institutions—not geography, climate, disease, or supposedly different cultures—shape prosperity and everyday security.

Setting and the border

The city is split by a fence. On its northern side lies Nogales, Arizona, in Santa Cruz County; immediately south is Nogales, Sonora, in a relatively prosperous part of Mexico. The two communities share the same local environment, and the book stresses that germs cross the border freely. Differences in health, therefore, are not explained by distinct disease conditions: inferior sanitation and inadequate health care south of the border contribute to poorer outcomes.

The border is also a relatively recent political division. After Mexico became independent from Spain in 1821, the area around Los dos Nogales remained Mexican, including after the Mexican-American War of 1846–1848. The Gadsden Purchase of 1853 extended the United States border into the region. Lieutenant N. Michler, surveying the border, noted the pretty little valley of Los Nogales; communities later grew on both sides. Their inhabitants share ancestors, food, music, and, the book suggests, much of their culture.

Everyday conditions north of the fence

The average household income in Nogales, Arizona, is about $30,000 a year. Most teenagers attend school, and most adults have graduated from high school. Residents are relatively healthy and live longer than people in many parts of the world; many older residents have access to Medicare. These outcomes sit alongside a wide array of public provisions that residents may take for granted: electricity, telephones, sewage and public-health systems, roads connecting the city to neighboring places and the rest of the United States, and law and order.

Security shapes ordinary economic life as well as public life. Residents can go about their activities without constant fear for their lives, theft, or the expropriation of investments in businesses and homes. The account presents that predictability as a practical condition for investing and working, not merely an abstract measure of prosperity.

Institutions and the contrast across the border

The book locates the decisive difference in the institutions governing the two sides. In Nogales, Arizona, people can choose occupations, pursue education and skills, and benefit when employers invest in better technology—conditions associated with higher wages. Political institutions also let residents participate in democracy, elect representatives, and replace officials who misbehave. Politicians, in turn, face citizens’ demands for services such as public health, roads, and public safety.

Nogales, Sonora, faces a different institutional setting. Household income is about one-third of the Arizona figure; many adults lack high-school degrees, many teenagers are not in school, infant mortality is higher, and life expectancy is lower. Roads and law enforcement are in worse condition, crime is high, and starting a business can mean risking robbery while struggling to obtain permissions and pay bribes. Before Mexico’s political reforms of 2000, the Institutional Revolutionary Party maintained corrupt control there, as it did across the country. The comparison therefore links institutional differences to divergent incentives for residents, entrepreneurs, and investors—and, ultimately, to markedly unequal prosperity.

A case within a larger history

Nogales is introduced as a starting point for a broader historical question: why institutions in the United States became more conducive to economic success than those in Mexico and much of Latin America. The answer, the book argues, lies partly in institutional divergence during the early colonial period. The city’s border makes that longer process legible in a small space: people with shared roots live under different rules and encounter different opportunities because they belong to different political and economic systems.

That argument is set against a wider account of how Atlantic commerce and European expansion shaped institutions. In England, the growth of trade and colonization created wealthy traders less dependent on the Crown, who pressed for limits on royal power; in other settings, European commercial and colonial expansion strengthened or imposed extractive institutions, sometimes destroying existing economic activity. The book’s examples include the Dutch East India Company’s forceful pursuit of spice monopolies in Southeast Asia and the destruction of independent polities and indigenous economies through colonial expansion. Nogales thus serves as an accessible opening contrast for an argument that institutional divergence has deep historical roots and consequences extending well beyond one border city.