[3] Vegetation is mostly steppe and shortgrass prairie, although pinyon and juniper trees are found in rocky canyons and cottonwoods and willows grow near streams.

[5] Beginning around the start of September, male tarantulas in the park will leave their burrows to search for females, which are in their own holes.

The Dust Bowl of the 1930s defeated the farmers and the Federal government bought the land comprising the present National Grassland from its bankrupt owners.

[11] An important addition occurred in 1991 when the U.S. Army transferred 16,000 acres (6,500 ha) of land in the Purgatoire River Canyon to the National Grassland.

The Army lands were part of the Piñon Canyon Maneuver Site (PCMS), a 238,000-acre (96,000 ha) facility devoted to military exercises.

[12] The expansion plan, to be implemented in several phases, would increase the size of the PCMS to several million acres, making it the largest military base in the United States.

If implemented, the plan would virtually eliminate private land ownership and ranching in Southeastern Colorado as well as abolish the National Grassland and displace 17,000 people.

[14] Picketwire Canyon is about 400 feet (120 m) deep and contains the Purgatoire River track site, one of the largest dinosaur track-ways in the world, in the Morrison Formation.

[15] The canyon and the dinosaur tracks are accessible by a hiking, biking, and horseback trail that leads 8.7 miles (14.0 km) one-way through the canyon to the Dolores Mission, the ruins of a small 19th century Catholic church, the dinosaur tracks, and the adobe-buildings of the Rourke ranch, which operated between 1871 and 1971 and is preserved as a National Historic Site.

There is a picnic area and eight miles of easy trails follow the mesa top or lead into the small, scenic canyon which has springs, old ruins, and rock art.

The Sierra Vista Overlook, Timpas Picnic Area, and Iron Springs preserve a section of the Santa Fe Trail.

Stone posts indicate the Santa Fe Trail and can be followed on foot for three miles between Sierra Vista and Timpas Picnic area.

It is a small canyon with easy slopes, large springs, picnic tables, and a loop hiking trail 2.6 miles (4.2 km) long.

A well-watered canyon with rock art, picnic tables, a hiking trail, and fishing for Channel Catfish in Carrizo Creek.