H030
Why does Hawaii have interstate highways?
Hawaii's nearest neighboring state is about 2,400 mi (3,860 km) away across the Pacific, yet the island of O‘ahu has four interstate highways. None of them could ever cross a state line.
“Interstate” describes the system, not each road. The highways' full official name is the Dwight D. Eisenhower National System of Interstate and Defense Highways. A road belongs to it because the federal government designated it and paid most of the cost, 90% in the system's early decades, not because it crosses a state line. Hawaii's routes were approved in 1960, a year after statehood, and they tie together the island's military bases: Pearl Harbor, Hickam, Schofield Barracks, and the Marine Corps base at Kāne‘ohe.
Hawaii isn't even unusual. Several mainland interstates never leave their state, including I-4 in Florida, I-45 in Texas, and I-97 in Maryland. A name tells you where something came from, not always what it is. Before trusting what a label says, ask how it's actually defined.
Try it somewhere else
Koalas look a little like small bears, and many people call them koala bears.
Is a koala a bear? What other names might mislead you about what something is?
The most expensive interstate ever built
H-3 cost about $80 million a mile. Approved in 1960 to connect Pearl Harbor with the Marine Corps base on the other side of the Ko‘olau mountains, it took 37 years of planning, lawsuits, and construction to open in 1997. Its final cost was $1.3 billion for 15.3 mi (24.7 km), making it the most expensive interstate ever built per mile, with tunnels through the mountains and long viaducts over valleys.
Alaska and Puerto Rico have interstates too
Alaska and Puerto Rico also have roads that count as interstates for federal funding, but they aren't signed as interstates and don't have to meet the same design standards. Hawaii's routes are the only signed interstates outside the lower 48 states, which is why H-1 is both the southernmost and the westernmost signed interstate in the country.
Related exhibits
Sources: Wikipedia, “Interstate Highway System” (official name; 90% federal funding; Alaska and Puerto Rico interstates); “Interstate Highways in Hawaii” (H-1, H-2, and H-3 approved in 1960; H-201 added in 1989); “Interstate H-1” (27.16 mi; southernmost and westernmost signed interstate); “Interstate H-2” (8.33 mi); “Interstate H-3” (15.32 mi; $1.3 billion; opened December 12, 1997; most expensive interstate per mile); “Interstate H-201” (4.1 mi, Moanalua Freeway); “Interstate 4,” “Interstate 45,” and “Interstate 97” (each entirely within one state). Distance to the nearest state is the approximate distance from Honolulu to California. Kilometers converted from miles.