The Philadelphia Suburban Transportation Company was incorporated in 1936 by the merger of the Philadelphia & West Chester Traction Company and the Philadelphia & Garrettford Street Railway Company.

The oldest element in the company's transportation system was the Philadelphia & West Chester Turnpike Road Company, which built a plank road from 42nd Street, Philadelphia, to Newtown Square in 1850-1851. It was converted into a macadam turnpike in 1856-1867 and was finally condemned by the state highway department in 1918. The Delaware County Passenger Rail Road Company built a horse car line along the turnpike as far as Upper Darby in 1859 but discontinued service in 1865, after which it was purchased by the turnpike company and torn up.

The Philadelphia, Castle Rock & West Chester Railway Company restored the line in 1895 using steam dummies, and the Philadelphia & West Chester Traction Company was organized on April 24, 1895, for the purpose of electrifying and operating the line. It also acquired the turnpike company. Electric trolley wire was installed in 1896, and the line was extended to West Chester in 1898. In 1899 the company passed into the hands of A. Merritt Taylor, who greatly expanded the system and used it to foster real estate development in the western suburbs.

Hoping to extend the line from West Chester to Coatesville, Taylor purchased the remnant of the old Philadelphia & Lancaster Turnpike in 1899. The extension was blocked by the Pennsylvania Railroad, and the turnpike was condemned by the state in 1901. In 1902 the Ardmore & Llanerch Street Railway Company completed a branch to Ardmore. Taylor formed the Eureka Light, Heat & Power Company in 1901 to sell surplus electricity to homeowners.

In 1903 work began on the Market Street elevated which greatly improved the travel time from center city to the western city line. Taylor was quick to exploit the possibilities this offered to real estate developers in the western suburbs. He organized the Philadelphia & Garrettford Street Railway Company in 1904 and constructed a high-speed trolley line on a private right of way from Upper Darby to Collingdale in 1906-1907. A branch was opened from Drexel Hill Jct. to Media in 1913, and the original line was extended to Sharon Hill in 1917. Taylor arranged for all his lines to meet the Market Street el. at a large terminal at 69th Street in Upper Darby in 1907, but opposition of the Philadelphia Rapid Transit Company prevented him from running his cars directly to center city over the el. as planned.

Small bus operators began to compete with Taylor's rail system in 1918. In 1923 he established the Aronimink Transportation Company as his own bus line, and it soon became the dominant bus company in the western suburbs. In 1940 the revenues from the bus lines surpassed those from the trolleys. A. Merritt Taylor retired in 1932 and was succeeded by his son Merritt H. Taylor.

The Philadelphia & Western Railroad Company was incorporated on May 21, 1902. It was sold at foreclosure in 1907 and reorganized as the Philadelphia & Western Railway Company. In the same year it opened a short suburban line from 69th Street to Strafford. The company was purchased by a group of Philadelphia bankers in 1910 for the purpose of securing a Philadelphia entry for their Lehigh Valley Transit Company, and a new line was opened from Villanova Jct. to Norristown in 1912.

Ridership on the P&W collapsed in the Depression, and the company engaged Dr. Thomas Conway, who had rehabilitated several interurban lines in the Midwest. He upgraded the property, shortened running times, and cut costs, and equipped the Norristown line with the Brill Bullets, lightweight aluminum streamlined cars that were the first of their type in the U.S. The company, however, remained in bankruptcy during the Depression.

Between 1943 and 1946, Merritt H. Taylor acquired control of the P&W, and the line was reorganized as the Philadelphia & Western Railroad Company. It was merged into the Philadelphia Suburban Transportation Company in 1953. Buses replaced trolley lines after World War II: the West Chester line was discontinued in 1954, the Strafford line in 1956, and the Ardmore line in 1966. In 1963 Merritt H. Taylor, Jr., bought the articulated, streamlined Electroliners from the Chicago, North Shore & Milwaukee for use on the Norristown line. The company maintained high levels of service until its properties were purchased by the Southeastern Pennsylvania Transportation Authority on January 29, 1970. The company was then renamed the Bryn Mawr Group, Inc., and became a Florida real estate company.