Charlotte Observer columnist Jeff Elder's "Glad You Asked" feature asks the question of where the first drive-through windows originated.
Although the answer isn't definitive, the first bank drive-through was in Dallas in 1938. For restaurants, the first drive-through is claimed on Route 66:
Some say Sheldon "Red" Chaney — a man of true genius — dreamed this up. In 1947 he opened Red's Giant Hamburgs on Route 66 in Springfield, Mo.
Why'd he call it Red's giant Hamburgs? Supposedly he measured the sign wrong and ran outta room. Genius.
At Red's, you drove up to the window and yelled your order into it. Genius.
Inside, the ceiling was painted blue and the floors painted green, so people who dined in would feel like they were on a picnic. Genius.
Regrettably, Red's Giant Hamburg has been gone for at least 15 years.
The first drive-through speaker box is linked to the In-n-Out regional burger chain in Los Angeles County, which also has plenty of Route 66 history.