For Andy Kim, college started at a cattle ranch.

The Democratic senator-elect from New Jersey spent the first two years of his undergraduate study at Deep Springs College, an isolated campus sequestered in the California desert 40 miles from the nearest town. Deep Springs’ pupils — never more than 30 in number — split their time between intensive seminar classes and the manual labor of running the college, which doubles as a functioning cattle ranch. In exchange for a full-ride scholarship, the college’s website states, “Deep Springs students are expected to dedicate themselves to lives of service to humanity.”

Kim would go on to earn his undergraduate degree from the University of Chicago, one of the nation’s most selective colleges. So would lots of his fellow lawmakers, many of whom graduated from the Ivy League or other highly selective institutions. More than 96 percent of Congress holds a bachelor’s degree or higher. Only two-fifths of American adults are similarly educated.

It’s a striking moment to examine the relationship between Congress and college, as higher ed becomes a political punching bag. America’s most influential colleges have faced increasing scrutiny in the wake of student protests over the Israel-Hamas war, with three presidents of Ivy League universities resigning their posts under pressure from Capitol Hill. And colleges are contributing to a political rift: Voters’ choices at the ballot box diverge along degree lines, with the college-educated more likely to vote blue. Democrats see their strong relationship with the college vote as a liability in an electorate increasingly souring on the value of a degree. Meanwhile, many of the Republican party’s strongest higher-ed critics themselves boast Ivy League degrees.

This comprehensive review conducted by The Chronicle — using data from the official congressional directory and campaign websites — examines the institutions that influence the nation’s future leaders.

Among two-year-college graduates, almost all also hold other degrees. Only one senator, Markwayne Mullin, holds an associate degree as his highest credential. More than 10 percent of American adults hold a similar degree.

Congress is disproportionately likely to graduate from a handful of highly selective institutions. One in 10 senators and 6 percent of representatives hold an undergraduate degree from one of the eight Ivy League colleges, which educate less than 1 percent of U.S. undergraduates.

Less than 4 percent of members hold undergraduate degrees from historically Black colleges and universities.