While AASHTO enjoys the full participation of all 50 state departments of transportation, along with the District of Columbia and Puerto Rico, it is not easy piecing together specifically when each state actually formally joined the association.

When initially established, AASHTO offered a dues option for individuals as well as state departments. So in some cases an individual from a specific state might have joined formally before the agency. However, in reviewing the year in which each state first paid dues — either for individuals or as a department — we can piece together some of the story.

Interestingly, in many cases, most states joined as a department of transportation after individual members joined and found value in participating.