As the industry leader at the turn of the century, PRR took to calling itself "The Standard Railroad of America," then broadend the slogan tp include "The World." In the 20th century the standardization was largly internal. Though PRR had 6,152 locomotives in 1929, a relative handful of types dominated the roster. Much of Pennsy's standardization was counter to most North American practice: Belpair Boilers on steam engines, position-light signals, electrification of main lines, numbering system that only belatedly grouped locomotives of the same class. tuscan red for passanger cars instead of dark green.
During WWII Pennsy's freight traffic doubled and passanger traffic quadrupled. After the war PRR had the same experiences as many other railroads but seemed slower to react, even considering the regulatory burdens then in place, under which all railroads labored. Pennsy was slower to dieselize, and when it did so it bought from every manufacturer. Freight and Passangers left for the highways, PRR found itself with too much fixed plant, and it was slow to take up excess trackage or install centralized traffic control. PRR was saddled with a heavy passanger buisness; it had an extensive commuter services centered on New York, Philadelphia, and Pittsburgh, and lesser ones Chicago, Washington, Baltimore, and Camden New Jersey. It had gone through the depression without going bankrupt, and so was never relieved of old debt obligations. PRR did maintain however the longest history of dividend payment in U.S. buisness history.
In 1957, the PRR and NYC, by then troubled twin giants more than rivals announced plans to merge. Penn Central began operations Feburary 1, 1968, and because the countries largest bankruptcy on June 21, 1970. That led to the formation of Conrail which took over seven bankrupt railroads on April 1, 1976 and became profitable in 1981.
