The borough of Canonsburg was incorporated in 1802, after having been founded by John Canon, who had built a flour and saw mill in the area. Canonsburg represents the mid-point between the start of the Branch at Carnegie, and the end of the Branch at Washington. In the early 1800s, the Jefferson College was the main draw of people and money into the city. After that college merged with the one in nearby Washington, PA, the Pennsylvania Railroad was encouraged to build a line between Mansfield (now Carnegie) and Washington, which would benefit Canonsburg's growing industries. Up until then, Canonsburg was a stagecoach stop between Pittsburgh and Washington. Coal was the main resource in the area.
By the early 1900s a trolley line was built between Canonsburg and Washington, which was later extended to Pittsburgh. Lots of immigrants moved into the town. The town survived the Great Depression due to its established factories. The city is well-known for its elaborate Fourth of July parades each year.
There were no oil dealers in the town (coal was available in abundance). There were likely some small coal dealers who received one or two hoppers. There were numerous other warehouses and wholesalers who had rail spurs and occasionally got box cars.
In 1911 Canonsburg annexes South Canonsburg. In 1912 oil was discovered in the area, leading to lots of oil wells being built. However, within a year the reservoir was pretty much depleted.
In 1919 Canonsburg buys its first American-LaFrance fire truck. In that same year they also annexed East Canonsburg. In 1923 Canonsburg annexed the White Lawn Terrace district (Standard Chemical Company and W.S. Pottery were integrated in that annexation).