Simplify the following text for a Grade 8 native English-speaking person.
Original: Using a stretch of highway from Amarillo , Texas to Tulsa , Oklahoma to form the original portion of Highway 66 , Avery spearheaded the creation of the U.S. Highway 66 Association to oversee the planning of Route 66 , based in his hometown of Tulsa .
Simplified: Avery used section of highway that was already built between Tulsa and Amarillo , Texas to make the original portion of Highway 66 . He was the main person responsible for making the U.S. Highway 66 Association to watch over the building of Route 66 .