It then continues east through the towns of Pearl City and Aiea for approximately five miles (8.0 km) to the complex Halawa Interchange, where it meets H-3 and H-201.

The highway then turns south for two miles (3.2 km), then east soon after the exits for Hickam Air Force Base and Pearl Harbor.

The H-1 and Nimitz Highway contraflow lanes are restricted to buses, motorcycles, and high-occupancy vehicles with two or more occupants while in operation.

A set of Interstate Highways serving Oʻahu were authorized by the federal government in 1960, a year after Hawaii was admitted as a state.

One of the corridors, connecting Barbers Point to Diamond Head, was designated as H-1 by the Bureau of Public Roads (now the Federal Highway Administration) on August 29, 1960.

[citation needed] Construction on the first new section of H-1 began in 1963, shortly after alignments were approved for most of the freeway.

[9] The Kapiolani Interchange, opened in October 1967, filled a gap between two sections of the Lunalilo Freeway spanning three miles (4.8 km) in Honolulu.

[10][11] Another gap in H-1 was filled in March 1969 with the opening of three miles (4.8 km) between Kunia Road (Route 76) and the Waiawa Interchange with H-2.