The Federal Highway numbering system began in 1925, the same year that the American Association of State Highway Officers (AASHO) came into being.
A timeline Washington State, with credit to History Link and the U.S. Dept of Transportation.
1853 - Washington State Legislature is formed, while still a territory. Franklin Pierce is the first territorial governor.
1889 - Washington becomes the 42nd state, on November 11th of that year.
1905 - WA State Highway board is formed. There are one thousand mile of roads and 600,000 residents in the state. Total cars: 100.
1911 - A road tax of 1-mill is established
1912 - The state begins experimenting with concrete
1917 - Locks on Seattle's ship canal are dedicated
1920 - The first airstrips go into service: one in Seattle at Sand Point, and one in Spokane.
1921 - The Columbia River Ferry goes into service. The state board becomes the highway committee, and consists of the governor, the state auditor, and the state treasurer.
1922 - Snow removal from roads in the cascades is started.
1930 - Keller Ferry opens
1935-1967 - Art Deco behemoth the Kalakala ferry in service.
Today there are six regional highway offices, each with a District Enginee.