The freeway portion of SR 1 from Highway 68 in Monterey to Munras Avenue opened in 1956–1960. The segment from Munras Avenue to the northern border of Sand City and Seaside opened in 1968, and bypasses the original highway alignment of Munras Avenue and Fremont Street in Monterey, and Fremont Boulevard through Seaside. North of Seaside, the freeway was built over the original SR 1 alignment through Fort Ord in 1973. North of Fort Ord, SR 1 now veers to the left of the original alignment and bypasses Marina to the west. This segment including the interchange with SR 156 and the short, 2-lane Castroville Bypass opened in 1976. Originally SR 1 followed the SR 156 alignment to the SR 183 intersection in Castroville, then turned northwest, following the present-day SR 183 through Castroville before rejoining its existing alignment at the northern terminus of the Castroville Bypass.