Originally occupied by a railroad line, planning for the East Busway began shortly after the Port Authority of Allegheny County purchased the Pittsburgh Railways Company in 1964.[2] The original segment of the busway opened in February 1983, running between Downtown Pittsburgh and Edgewood, a length of 6.8 miles.
In 2003, the busway was extended into Swissvale by 2.3 miles (3.7 km), making its current length 9.1 miles (14.6 km).
Following the naming convention of each busway being designated by a color, bus routes that use the East Busway begin with a "P" for purple. However, the P13 (Mount Royal Flyer) is colored purple and uses a "P" designation, but does not use the busway; instead, it travels via Route 28. The P1 ("East Busway All Stops") is the main route, operating seven days a week and running the full length of the Busway between Swissvale and Downtown Pittsburgh, making all stops, before running a short loop through the central business district. It is the busiest Pittsburgh Regional Transit bus route by ridership.
All busway routes travel to downtown Pittsburgh, making a loop around before returning via the busway. The one exception to this is the P3 (East Busway-Oakland), which starts in Swissvale, but leaves the busway via the Neville Street Ramp, serving the business district of Oakland and terminating at Robinson Street.
Many of Pittsburgh Regional Transit's express and suburban Flyer routes also use the busway, but with stop restrictions, not picking up passengers at some busway stations in the inbound direction or dropping off passengers at some busway stations in the outbound direction. These routes operate primarily during weekday rush hours allowing buses to bypass the heavily congested Parkway East (Interstate 376), making for faster trip times. The East Busway is also used by some Westmoreland Transit routes, which run further into the Pittsburgh suburbs, ending in the cities of Greensburg and Latrobe in Westmoreland County.
As of February 2024, the Pittsburgh Regional Transit bus routes that use the East Busway are as follows:[4]