Although he was a native of Pennsylvania, his lifetime business endeavors would help shape the early phase of the oil industry in Texas.

Oil was discovered in Corsicana, Texas, in 1894 by accident when a water-well company found petroleum while digging a well for the city.

The lack of refineries often resulted in dumping of crude oil, a wasteful practice which prompted Texas legislators to enforce regulations on the industry.

[2] Cullinan, a key person in the development of the state's first petroleum-conservation statute, took such an interest that he agreed to build a refinery.

The Texas Fuel Company was formed on March 28, 1901, and went into production on January 2, 1902, with an initial 40 acres (160,000 m2) of land at Port Arthur and a storage site 1+1⁄2 miles (2.4 km) from Spindletop.

In addition to being one of the key supporters for the development of the Houston Ship Channel, he also built the North Side belt railway.

In 1895, he ventured into the manufacture of steel storage tanks and started his own company under the name Petroleum Iron Works in New Castle, Pennsylvania.

Afterward his interest in Texaco was split six ways between his sister Mary Nicholson and his children, including daughter and philanthropist Nina J.