See Ancient Rock Art Petroglyphs Near Yellowstone
Petroglyphs and pictographs - some 12,000 years old - can be viewed in the Yellowstone region. Sites are in Wyoming, Utah, and Montana.
Petroglyphs are incised, chipped or carved onto rock walls, while pictographs are made by painting pigment on the rock surface. They are important in determining what the ancient people were like who once lived in these areas.
Legend Rock State Petroglyph Site near Thermopolis, Wyoming

Legend Rock is located about 20 miles from Thermopolis. This protected site contains at least 283 different petroglyphs on 92 individual sandstone panels. The gate to the area is locked. To get driving directions and a key to access Legend Rock, stop in at the Hot Springs State Park office located at the entrance of the state park in Thermopolis.
At the Legend Rock site, visitors will see illustrations of human figures, animals and abstracts. (http://thermopolis.com/attractions/petroglyphs/)
Mike Bies, an archaeologist in the Worland, Wyoming, BLM office, recommends two sites in the Bighorn Basin in northern Wyoming: Legend Rock and the Medicine Lodge State Archaeological Site. Both are “drop-dead amazing” for their concentrations of rock art that aren’t found elsewhere, Bies says. (http://wyoparks.state.wy.us/Site/SiteInfo.aspx?siteID=25)
White Mountain Petroglyphs near Rock Springs, Wyoming
Located in the Red Desert in southwestern Wyoming, the White Mountain Petroglyphs are also worth a visit. To get there, travel approximately 10.5 miles north from Rock Springs on U.S. Highway 191 and turn east (right) onto the Tri-Territory Road (County Road 4-17). Go approximately 10 miles on the Tri-Territory Road, and take a left when you see a sign marking the White Mountain Petroglyphs.
Nine Mile Canyon in Utah

In northeastern Utah, ancient Fremont Indians left behind numerous rock art panels. The best of these is Nine Mile Canyon, considered by many to be the longest natural art gallery in the world. Featured in National Geographic, this scenic desert canyon has numerous rock art panels scattered along a self-guided auto tour.
Dry Fork Petroglyphs near Vernal, Utah

The Dry Fork Petroglyphs, located just outside Vernal, are well known for their quality and accessibility. These 800-year-old Fremont Indian panels cover 200 feet of a Navaho Sandstone cliff face.
Pictograph Cave State Park near Billings, Montana

In Montana, see 4,500-year old pictographs at Pictograph Cave State Park, located seven miles southeast of Billings off I-90. Take the Lockwood Exit, then travel six more miles on county roads. (http://stateparks.mt.gov/pictograph-cave/)