The acronym “UC” was used by the University of Colorado for fifty years, beginning when the university opened in 1876. Around 1924-25 “CU” became the official abbreviation, presumably to distinguish Colorado from the University of California. Coincidentally, other schools in the Big 12 Conference also use this reverse acronym. For example, the Universities of Kansas and Oklahoma are known as KU and OU, respectively.
According to University Communications, the current official name of the Boulder campus is the University of Colorado Boulder. The preferred second reference to the campus is CU-Boulder. UCB should only be used in campus addresses.
Note: The official name of the four-campus system is the University of Colorado, and the acronym is CU. Use only when referring to the whole university.