“Are you an American, or are you not?” This was the question Harry Wheeler, sheriff of Cochise County, Arizona, used to choose his targets in one of the most remarkable vigilante actions ever carried out on U.S. soil. And this is the question at the heart of Katherine Benton-Cohen’s provocative history, which ties that seemingly remote corner of the country to one of America’s central concerns: the historical creation of racial boundaries.

It was in Cochise County that the Earps and Clantons fought, Geronimo surrendered, and Wheeler led the infamous Bisbee Deportation, and it is where private militias patrol for undocumented migrants today. These dramatic events animate the rich story of the Arizona borderlands, where people of nearly every nationality—drawn by “free” land or by jobs in the copper mines—grappled with questions of race and national identity. Benton-Cohen explores the daily lives and shifting racial boundaries between groups as disparate as Apache resistance fighters, Chinese merchants, Mexican-American homesteaders, Midwestern dry farmers, Mormon polygamists, Serbian miners, New York mine managers, and Anglo women reformers.

Racial categories once blurry grew sharper as industrial mining dominated the region. Ideas about home, family, work and wages, manhood and womanhood all shaped how people thought about race. Mexicans were legally white, but were they suitable marriage partners for “Americans”? Why were Italian miners described as living “as no white man can”? By showing the multiple possibilities for racial meanings in America, Benton-Cohen’s insightful and informative work challenges our assumptions about race and national identity.

In 1907 the U.S. Congress created a joint commission to investigate what many Americans saw as a national crisis: an unprecedented number of immigrants flowing into the United States. Experts—women and men trained in the new field of social science—fanned out across the country to collect data on these fresh arrivals. The trove of information they amassed shaped how Americans thought about immigrants, themselves, and the nation’s place in the world. Katherine Benton-Cohen argues that the Dillingham Commission’s legacy continues to inform the ways that U.S. policy addresses questions raised by immigration, over a century later.

Within a decade of its launch, almost all of the commission’s recommendations—including a literacy test, a quota system based on national origin, the continuation of Asian exclusion, and greater federal oversight of immigration policy—were implemented into law. Inventing the Immigration Problem describes the labyrinthine bureaucracy, broad administrative authority, and quantitative record-keeping that followed in the wake of these regulations. Their implementation marks a final turn away from an immigration policy motivated by executive-branch concerns over foreign policy and toward one dictated by domestic labor politics.

The Dillingham Commission—which remains the largest immigration study ever conducted in the United States—reflects its particular moment in time when mass immigration, the birth of modern social science, and an aggressive foreign policy fostered a newly robust and optimistic notion of federal power. Its quintessentially Progressive formulation of America’s immigration problem, and its recommendations, endure today in almost every component of immigration policy, control, and enforcement.