The sharp and sweeping rise of racial segregation in 20th century America

Before the Census was mailed to every household in America, it was gathered by counters walking door-to-door who collected along the way an inadvertent historical record not just of who we were in 1880 or 1940, but who we lived next to.

Buried in that record is a fascinating picture of race and residential segregation both more detailed and more sweeping than how we've typically looked at it: The hand-drawn enumerator forms of a century ago show where black families lived right next to white ones, or where entire streets were lined with households of a single race. They show, in other words, where Americans were integrated not across entire cities, but across fence posts and brick walls. They show patterns of fine-grained racial segregation that are impossible to see in public Census data today where privacy concerns override precision.

"It’s sort of shocking how much you can know about these historical patterns," says John Parman, an economist at the College of William and Mary, "especially relative to these modern studies."