The 58,000-acre San Pedro Riparian National Conservation Area protects some 40 miles of the upper San Pedro River between St. David and the border. There are about 400 species of birds here, 82 mammal species, and 45 reptile and amphibian species, some of which you’re likely to see if you stay vigilant and quiet while exploring. Beavers, once plentiful in the now nearly extinct riparian habitats of Southern Arizona, have been reintroduced here.

The Friends of the San Pedro River have converted a 1930s-era ranch house—in the shade of a beautiful 120-year-old Fremont cottonwood tree—into the San Pedro House gift shop and bookstore (9800 Hwy. 90, 520/508-4445, daily 9:30 a.m.–4:30 p.m.), where you can pick up information and pamphlets for a self-guided river walk and other trails and get advice from the volunteers.

Here you’ll also find the Murray Springs Clovis Site and Trail, a kind of stone-age butcher shop frequented by Clovis people 8,000–11,000 years ago. Scientists have dug up the fossils of several huge extinct mammals here, some of which are currently housed at the Museum of Natural History in New York.