"During the 2011--12 school year, about two-thirds (68%) of the more than 900 U.S. 4-year colleges and universities with 2,500 or more students used sworn police officers to provide law enforcement services on campus. Sworn police officers have full arrest powers granted by a state or local authority. The percentage of public institutions (92%) using sworn officers was more than twice that of private institutions (38%). Similar to sworn officers, about two-thirds of campuses were served by armed officers. The percentage of public campuses (91%) using armed officers was also more than double the percentage of private institutions (36%). Among public institutions, nearly all students were enrolled on campuses with sworn (96%) and armed (94%) officers. Among private institutions, nearly half of the students were enrolled on campuses with sworn (46%) and armed (45%) officers. These findings come from the 2011--12 Survey of Campus Law Enforcement Agencies, the first conducted by the Bureau of Justice Statistics (BJS) since the 2004--05 school year. Among the institutions contacted for both the 2004--05 and 2011--12 BJS surveys, the percentage using sworn officers increased from 75% to 77%, and the percentage using armed officers increased from 68% to 75%. A majority of the campuses with sworn police officers also used nonsworn security officers. Overall, 41% of campuses were served by both types of officers. About a third of campuses (32%) were served by nonsworn officers exclusively. The percentage of campuses using sworn officers ranged from a high of 96% among public campuses with 10,000 or more students to a low of 30% among private campuses with 2,500 to 4,999 students."
Bureau of Justice Statistics: http://www.bjs.gov/