From the National Park Service:
Capulin Volcano National Monument is a well-preserved, relatively young (58,000 to 62,000 years old), symmetrical cinder cone. It rises steeply from the surrounding grassland plains to an elevation of 8,182 feet above sea level. The irregular rim of the crater is about a mile in circumference and the crater about 400 feet deep.
Capulin Volcano is one of the outstanding landmarks located in the northeast corner of New Mexico, where the rolling grasslands meet the foothills of the Sangre de Cristo Mountains. Capulin Volcano's highest point provides unobstructed, panoramic views of the volcanic field, distant snow-capped mountains, and portions of four states (New Mexico, Oklahoma, Texas and Colorado). Capulin Volcano also offers visitors excellent opportunities for observing and understanding volcanic formation. The large volcanic field surrounding the monument contains at least 100 recognizable volcanoes, and aids visitors in gaining insights into 10 million years of the geological history of northern New Mexico.
On January 16, 1891, Capulin Mountain was "…withdrawn from settlement, entry or other disposition under any of the public land laws, until such time as Congress may see fit to take action touching the same or until otherwise ordered by competent authority…"
On August 9, 1916, President Woodrow Wilson set Capulin aside as a U.S. National Monument by Presidential Proclamation No. 1340, to preserve "…a striking example of recent extinct volcanoes … which …is of great scientific and especially geologic interest…"
Public Law 87-635, 87th Congress, S.2973, September 5, 1962, amended the proclamation to "…preserve the scenic and scientific integrity of Capulin Mountain National Monument…" because of the significance of Capulin Volcano.
On December 31, 1987, Congress changed the Monument's name from, Capulin Mountain National Monument to Capulin Volcano National Monument, by Public Law 100-225 (101 Stat. 1547).