| Title | Date | Type | Setname | ||
|---|---|---|---|---|---|
| 301 |
 | Barrett Christy [21] | 2000 | Image | uum_map_usa |
| 302 |
 | Barrett Christy [22] | 2000 | Image | uum_map_usa |
| 303 |
 | Barrett Christy [23] | 2000 | Image | uum_map_usa |
| 304 |
 | Barrett Christy [24] | 2000 | Image | uum_map_usa |
| 305 |
 | Barrett Christy [25] | 2000 | Image | uum_map_usa |
| 306 |
 | Battle Rock, McElmo Creek, SW Colorado | 1915 | Image | uum_map |
| 307 |
 | Bear | 1910; 1911; 1912; 1913; 1914; 1915 | Image | dha_wehgn |
| 308 |
 | Beaver | 1950; 1951; 1952; 1953; 1954; 1955; 1956; 1957; 1958; 1959; 1960; 1961; 1962; 1963; 1964; 1965; 1966; 1967; 1968; 1969; 1970; 1971; 1972; 1973; 1974; 1975; 1976; 1977; 1978; 1979; 1980; 1981; 1982; 1983; 1984; 1985; 1986; 1987; 1988; 1989 | Image | uum_map_rr |
| 309 |
 | Beaver Creek | 2006; 2007 | Image/StillImage | uum_map_usa |
| 310 |
 | Below Harding [Hole] | 1954-08 | Image | uum_map_rr |
| 311 |
 | Below Red Dirt Creek | 1933 | Image | uum_map_rr |
| 312 |
 | Berthoud Pass plaque | 1985 | Image/StillImage | uum_map_rr |
| 313 |
 | Bill and Alley Gadd | 1942; 1943; 1944; 1945 | Image/StillImage | ucl_rhc |
| 314 |
 | Birds on shore, Yampa River | 1976 | Image | uum_map_rr |
| 315 |
 | Bjorn Leines competing in the X-Games | 1998 | uum_map_usa | |
| 316 |
 | Bjorn Leines competing in the X-Games. | 1998 | uum_map_usa | |
| 317 |
 | Bjorn Malkomsen, Crested Butte, Colorado, 1970 [1] | 1970 | uum_map_usa | |
| 318 |
 | Bjorn Malkomsen, Crested Butte, Colorado, 1970 [2] | 1970 | uum_map_usa | |
| 319 |
 | Black Canyon of Gunnison | 1908-07-17 | Image | dha_scp |
| 320 |
 | Black Canyon of the Gunnison | 1908-07-17 | Image | dha_scp |
| 321 |
 | Black Canyon of the Gunnison | 1908-07-17 | Image | dha_scp |
| 322 |
 | Black Canyon of the Gunnison River, Colorado | 1883 | Image/StillImage | uum_map |
| 323 |
 | Black Canyon of the Gunnison River, Colorado | 1883 | Image/StillImage | uum_map |
| 324 |
 | Black Canyon of the Gunnison River, Colorado | 1883 | Image/StillImage | uum_map |
| 325 |
 | Black Canyon of the Gunnison River, Colorado | 1883 | Image/StillImage | uum_map |