Hoedown is on target. Here are the numbers I have from the US Department of Education:
Total number of 4 year degree granting institutions: 2364
Public 4 year institutions: 612
Doctoral level publics: 166
Master's level publics: 282
Bac. only publics: 101
Other 4 year degree granting publics: 63
Private 4 year colleges: 1752
Doctoral level privates: 86
Master's level: 386
Bac. only: 546
Other: 742
The U.S. News & World Report "ranking" includes approximately 1400 4-year colleges.
If you want to see the breakdown by state, go to the site where I pulled these numbers from:
http://nces.ed.gov//programs/digest/d02/dt244.asp