Formed in 1946, Sierra Sky Park Airport is a residential airport community born of a unique agreement in transportation law to allow personal aircraft and automobiles to share certain roads. Sierra Sky Park was the first aviation community to be built[citation needed] and there are now numerous such communities across the United States and around the world. Developer William Smilie created the nation's first planned aviation community. Still in operation today, the public use airport provides a unique neighborhood that spawned interest and similar communities nationwide.