educate the public about our history

U.S. Route 395, also known as the “Three Flags Highway” stretches nearly 1,500 miles in a route that connected three countries: Mexico, United States and Canada. It was officially designated U.S. Highway 395 in 1939 as it served as one of Southern California’s earliest major north–south highways. 

During World War II, the U.S. military relied on this corridor to move service personnel and equipment between March Air Field and deployment bases in San Diego. Daily convoys passed through the small rural communities of Perris, Menifee, Lake Elsinore, and Murrieta bringing a steady stream of military traffic through the area.

 In 1952, engineers completed “The Big Cut,” blasting through the hard rock of the Menifee Hills to create a modern highway alignment linking Perris, Menifee, Murrieta, and Temecula with San Diego County. Crews reportedly used about 12,000 tons of dynamite to carve the new corridor.  The scale of the blasting reflected the difficulty of carving a safe and efficient corridor through the rugged terrain, a route essential for both military and civilian transportation. This black‑and‑white photograph captures this pivotal moment, showing the newly carved passage. 

By 1953–1954, U.S. Highway 395 was fully realigned eastward through Temecula, Murrieta, Menifee, Sun City, and Perris, becoming southern Riverside County’s first major expressway system. This upgraded corridor laid the foundation for the region’s modern transportation network and ultimately evolved into the 15E and today’s Interstate 215. The accompanying photograph was taken at Newport Road and 15E in the early 1970s.

In partnership with the City of Menifee, we are proud to recognize the historic route that passes through the Menifee Valley with the installation of the signs (Antelope Road north of Scott Road and Encanto Drive near Chambers Avenue).