The forum doctrine has been applied in situations in which government-owned property or a government program was capable of accommodating a large number of public speakers without defeating the essential function of the land or the program. For example, a park can accommodate many speakers and, over time, many parades and demonstrations. The Combined Federal Campaign permits hundreds of groups to solicit donations from federal employees. See Cornelius, 473 U.S., at 804-805, 105 S. Ct. 3439, 87 L. Ed. 2d 567. A public university's student activity fund can provide money for many campus activities. See Rosenberger, 515 U.S., at 825, 115 S. Ct. 2510, 132 L. Ed. 2d 700. A public university's buildings may offer meeting space for hundreds of student groups. See Widmar v. Vincent, 454 U.S. 263, 274-275, 102 S. Ct. 269, 70 L. Ed. 2d 440 (1981). A school system's internal mail facilities can support the transmission of many messages to and from teachers and school administrators. See Perry Ed. Assn., 460 U.S., at 39, 46-47, 103 S. Ct. 948, 74 L. Ed. 2d 794. See also Arkansas Ed. Television Comm'n v. Forbes, 523 U.S. 666, 680-681, 118 S. Ct. 1633, ...