Lets look at the early 20th century for a comparison:

In 1900 there were 8,000 registered automobiles in the U.S.

http://www.usnews.com/usnews/culture/articles/991227/archive_004572_6.htm

In 1910 there were 458,500 registered automobiles in the U.S.

http://web.bryant.edu/~ehu/h364/materials/cars/cars%20_20.htm

Gas Stations actually didn’t exist but if you count a roadside pump as a gas station, there were never as many pumps as cars. The full service gas station came later and, never did become as numerous as the cars. Since 1990, when gas stations peaked at 200,000, the number of gas stations in the USA has gone down.

I think they will be gone in less than 20 years or changed to EV quick charge/snack shops.

“The first public gasoline servers were simply called filling stations. They were just curbside hand pumps, and they began appearing in 1907. There was no service in 1907, either. You did your own repairs in those days.

Henry Ford and the great explosion of automobiles after WW-I changed all that. Those millions of new cars needed a huge infrastructure of supply. So a new American institution came into being. It was what we called the gas station.

The gas station started taking shape around 1910. By 1920 it was well-defined. It was a small building with gas pumps in front. But it also offered supplies — tires, batteries, and oil. It offered simple services — lube jobs and tire patching.

In 1920, America had 15,000 gas stations and only half that number of curbside pumps. By 1930, we had over 100,000 gas stations, and curbside pumps had all but vanished. ”

http://www.uh.edu/engines/epi975.htm