Catholic schools have historically made up a significant portion of American primary and secondary educational institutions. However, the number of Catholic schools and attendance in those schools declined sharply between 1960 and 1990.
Despite a growing Catholic population (from 45 million in 1965 to almost 77 million today, making it the largest Christian denomination in the United States), enrollment in Catholic schools has plummeted, from 5.2 million students in nearly 13,000 schools in 1960, to 2.5 million in 9,000 schools in 1990.
After a promising increase in the late 1990s, enrollment had by 2006 dropped to 2.3 million students in 7,500 schools. This steep decline would have been even steeper if these sectarian schools had had to rely on their own flock for enrollment: almost 14 percent of Catholic school enrollment is now non-Catholic, up from less than 3 percent in 1970.
When Catholic schools educated 12 percent of all schoolchildren in the United States, in 1965, the proportion of Catholics in the general population was 24 percent. Catholics still make up about one-quarter of the American population, but their schools now enroll less than 5 percent of all students.
Since 1990, however, the decline has slowed. In the twenty years from 1990 to 2010, enrollment in Catholic schools declined from 2.5 million to 2.1 million. But only about 600,000 of that enrollment is in Catholic high schools. Thus more than 95% of Catholic high school students are in atheistic public school.