This paper documents how segregation between Black students and White students across U.S. colleges has evolved since the 1960s, explores potential channels through which changes occur, and studies segregation across majors within colleges. The main findings are: (1) Black-White dissimilarity fell sharply in the late 1960s and early 1970s and has fallen more gradually since then. White students' exposure to Black students rose almost continuously from 1968 through 2011 before declining somewhat in recent years. Meanwhile, Black students' exposure to White students increased sharply in the late 1960s and early 1970s and has fluctuated since. (2) There has been regional convergence, although colleges in the South remain more segregated than those in any other region when measured by dissimilarity or by Black students' exposure to White students. (3) A major channel for the decline in segregation is the declining share of Black students attending historically Black colleges and universities. Differences in which U.S. state students attend college play only a small role in creating segregation, and there is moderate evidence that segregation is related to college selectivity stratification by race. (4) Although there is segregation within universities, most segregation across major x university cells occurs across universities.