This distribution network was already in place under both Rockefeller's Standard Oil and Ludwig Nobel's (of the Swedish Noble family) Russian Branobel. However, this wasn't set up initially for gasoline but for kerosene.

In the late 19thC whale fat and tallow were mainly used for light but the smell was unpleasant and the light very poor. However in the 1860's petroleum wells in Pennsylvania and Ontario started producing kerosene which is neutral smelling and

"gives a light which leaves little to be desired (Beecher-Stowe)."

This was the actual start of petroleum distribution. Originally the kerosene would be transported in wood barrels (which is still the standard measurement of petroleum) by horse and carriage especially in the hinterlands. However, as demand increased after the Civil War,

"One innovation was the railway tank car, which eliminated the need to pile barrels into a boxcar. Standard replaced barrels on the streets of America with horse-drawn tank cars, which could disburse...anything from a pint to 5 gallons (Williamson and Daum, Age of Illumination)

Ludvig meanwhile figured out a ballast issue in shipping oil and commissioned the first oil tanker the Zoroaster in 1878 to supply the ever-oil-hungry Russian capital. So even early on in the late 1800's bulk transportation was becoming the norm. It's actual point of sale was out of bulk goods retailers and the like. Even the smallest towns in America had kerosene by the late 1800's.

Rockefeller's Standard Oil (kerosene) came to dominate the market and his "vertical integration" of owning all parts of oil production greatly streamlined both output and delivery (this is and has always been very controversial). Gasoline was being distributed at this point but it was only used as a solvent.

Then electrical lighting came in and threatened to undue the petroleum industry if it wasn't for cars. Cars essentially saved the industry and Rockefeller (and the other oil men) quickly changed to gasoline as their industry at that point was in bad shape.

You can read more in an amazing but long and very thorough book The Prize by Daniel Yergin.

Hope that helps!