Interstate 1 (I-1) is an Interstate Highway running parallel along very closely to the Pacific Coast of the United States from Dana Point, California to Grant Pass, Oregon. It is one of the two coastal major Interstate Highways in the United States, the other one being Interstate 101 (I-101), which runs parallel closely to the Atlantic Ocean. The southern terminus is at Interstate 5 (I-5) in Dana Point, California. The northern terminus is at Interstate 5 (I-5) in Grant Pass, Oregon. The interstate is only in the states of California and Oregon. Interstate 1 and Interstate 101 are the only two major north-south interstates ending in 1, while the other north-south major interstates ends in 5.
In California, the entire highway is known as the Pacific Coast Freeway. From Santa Monica to Dana Point, it is known as the Dana Point Freeway. It is one of the state's most famous freeways and highways. The entire interstate is parallel to California State Route 1 (CA 1), U.S. Route 101 (US 101), and partly Interstate 5 (I-5) and U.S. Route 99 (US 99). The interstate provides great scenic view of the Pacific Ocean and the mountains passed by the interstate, forcing each direction to split out. The southbound always parallels the Pacific Ocean while the northbound passes the mountains. However, tunnels are involved, allowing the interstate to go through the mountains. I-1 travels through the coastal cities in California including Long Beach, Santa Monica, Malibu, Oxnard, Ventura, Santa Barbara, Santa Maria, Morro Bay, Ooscondio, Nacimiento, Santa Cruz, San Francisco, Golden Gate City, and Crescent City.
In Oregon, I-1 is in the southwestern corner of the state. After sharp turning inland, leaving the California Pacific coast near Crescent City, I-1 heads northeast as it parallels U.S. Route 199 (US 199) to the California–Oregon border between Idlewood, California and O'Brien, Oregon until I-1 and US 199 terminates in Grant Pass at I-5. Interstate 5 on the other hand, acts as a bypass route through the coastal cities.
In Dana Point, after Interstate 5 (I-5) is done paralleling the Pacific Coast and turning inland as the Santa Ana Freeway, I-1 takes over and begins in Dana Point as I-5 and I-1 splits southeast of the city. I-1 begins as the Pacific Coast Freeway. The highway starts sharing routes with California State Route 1 (CA 1) as it runs northwards leaving Dana Point then next up is Laguna Beach, where California State Route 133 (CA 133) begins at I-1. Next is Newport Beach, where California State Route 55 (CA 55) begins as it heads to Costa Mesa becoming a freeway. As I-1 starts paralleling Interstate 405 (I-405), it heads to Huntington Beach, where California State Route 39 (CA 39) begins.
