In a 1902 article in the Daily Notes, Canonsburg's local newspaper, it stated that the railroad carried an average of 4,500 passengers a day. For a circus or a parade, the railroad could be expected to haul 10,000 people to Pittsburgh, PA.
At that time, there were 12 trains daily, 9 of which went all the way between Washington, PA and Pittsburgh. There were just two scheduled runs on Sundays. The PRR created an express train in July 1889 between Washington and Pittsburgh that stopped only at Canonsburg and Bridgeville. It was known as the "Cannonball", traveling at a blistering 32 miles per hour! The morning train, #118 (#117 was the same run in reverse from Pittsburgh back to Washington), left Washington at 8:45am, departed Canonsburg at 8:58am, Bridgeville at 9:14am, and arrived at Pittsburgh at 9:40am. Before this, the "fast" train to Pittsburgh, #122, had left Washington at 7:30am, with scheduled stops at Canonsburg, Bridgeville, and Mansfield (now Carnegie), and arrived at Pittsburgh at 8:50am. However, it would make flag-station stops at Meadowlands, Morganza, and Woodville.
The city council of Canonsburg thought 32mph was way too fast and they voted to force an 8mph top speed for the PRR trains coming through their town. The PRR stubbornly ignored that order and subsequently removed Canonsburg as one of its stops. The issue was eventually resolved when a compromise of 20mph was reached and a watchman added by the railroad in two locations in town. By 1904 the Canonball trains were clocked at going 60mph between the towns.
Before WWII, there were 9 regularly-scheduled passenger trains every day, 10 on both Thursday and Friday, and 11 on Saturday. Passenger trains also carried milk from the farms in northern Washington county. Up until the late 1940s, there continued to be large volumes of passenger traffic.
After WWII, trains were only one or two cars long, using either P54, P70, or PB54 cars. Special-events trains, such as area schools' picnic days, could pull 4 to 7 P70 coach cars, which would use K4 locomotives. A schedule for one such train from the late-1930s or early-1940s appears on page 102 of the book Kennywood... Roller Coaster Capital of the World by Charles J. Jacques, Jr.
The last scheduled passenger train made its final stops in the evening of on July 30, 1952. It was pulled by a K4 steam locomotive, #3489, that with a tender nearly too long for the turntable at Washington.