It begins in the San Joaquin Valley at Interstate 5 near Gustine, and runs east into Sierra Nevada, terminating in Yosemite National Park.

Western meadowlarks, American kestrels, red-tailed hawks and turkey vultures are frequently glimpsed.

The highway then runs alongside the Merced River for about 20 miles (32 km) to the Yosemite National Park entrance, after passing through El Portal.

[7] The "All-Weather Highway" (now State Route 140) opened in 1926, ensuring year-long visitation and delivery of supplies under normal conditions.

[8] A small detour opened in August, 2006, with a traffic light system to allow drivers to circumvent the original slide damage area.

Plans are underway for construction of a rock shed through the slide area to restore the original alignment.

Except where prefixed with a letter, postmiles were measured on the road as it was in 1964, based on the alignment that existed at the time, and do not necessarily reflect current mileage.