The airport where I did my first solo flight was a closed section of the “old highway” next to the new interstate….a 2,115′ x 32′ road-turned-runway built in 1954. This guy had almost a mile of 40+’ wide highway.
An average runway is 5,500′ x 75′ for a small airport upto 15,000′ x 200′ for a runway at JFK, DFW, or LAX.