Title: Buffalo, Rochester and Pittsburgh Railway
Content:  The Buffalo, Rochester and Pittsburgh Railway thrived on the haulage of heavy freight, primarily Pennsylvania coal, but its passenger service was characterized as "second to none". The first passenger run took place on the Rochester and State Line Railroad on its 15 September 1874 run from Rochester to Le Roy. The last was on 15 October 1955, when the Baltimore and Ohio Railroad ended its Buffalo - Pittsburgh service. At the start of the 20th century, the BR&P inaugurated a through service connecting Rochester and Pittsburgh. The first run of the Pittsburgh Mail and Express left Rochester at precisely 0900 on 10 October 1899, bound for Pittsburgh, 330 mi to the south. The night departure was 
Title: Pennsylvania Railroad
Content:  where it connected with the Reading Railroad for its competing Royal Blue Line passenger trains to reach New York. In 1885, the PRR began passenger train service from New York City via Philadelphia to Washington with limited stops along the route. This service became known as the "Congressional Limited Express." The service expanded, and by the 1920s, the Pennsy was operating hourly passenger train service between New York, Philadelphia and Washington. In 1952, 18-car stainless steel streamliners were introduced on the Morning Congressional and Afternoon Congressional between New York and Washington, as well as the Senator from Boston to Washington.
Title: Pittsburgher
Content:  The Pittsburgher was an overnight limited passenger train operated by the Pennsylvania Railroad between New York City and Pittsburgh, Pennsylvania over the Pennsylvania's Main Line. It operated from 1924 to 1964 and one of the most prestigious trains operated by the Pennsylvania and perhaps the premier train between New York and Pittsburgh.
Title: Connecting Railway
Content:  The Connecting Railway mainline was operated as part of the PRR mainline from Philadelphia to New York, providing through and local passenger service and extensive freight service to the many industries located in northern Philadelphia. The main passenger station on the line was North Philadelphia station. Because of the northern alignment of the Connecting Railway, passenger trains between New York and Pittsburgh would stop there only, bypassing 30th Street Station. The Chestnut Hill, Fort Washington and Bustleton Branches also saw passenger service; the other lines were exclusively freight lines. In particular, the Kensington & Tacony Branch served the upper Philadelphia waterfront and the Frankford Arsenal, and the Oxford Road Branch served a Sears distribution center near its crossing of the Reading. Passenger service on the Bustleton Branch was discontinued in 1926, but the Chestnut Hill and Fort Washington Branches became part of the PRR suburban electrification program. Electrified service from Chestnut Hill to Broad Street Station began in 1918 and over the Fort Washington Branch in 1924. The rest of the mainline was electrified by 1935 to allow electric service to New York.
Title: Pittsburgher
Content:  The Pittsburgher began operation on January 14, 1924. The Pittsburgher was the premier Pennsylvania train operating between New York and Pittsburgh. Although not streamlined in 1938 as part of the "Fleet of Modernism", it was completely upgraded with streamlined equipment (but with no observation car) at the express request of U.S. steel business clientele. Although the train was considered all-Pullman, it frequently carried coaches on the end for day travelers going to Pittsburgh and back. In 1944, the Pittsburgher was discontinued as part of a government order that prohibited the use of sleeping cars between points less than 450 mi apart so the government could free up sleeping cars for the war effort. The next day, it was reinstated as a day train between the two points. By late 1945, it was back to running as an overnight, all-Pullman train between New York and Pittsburgh. Service was discontinued in 1964, and its sleepers were transferred to the Manhattan Limited.
Title: Northeast Corridor
Content:  which was the terminus of electrified service for over 80 years. The PRR was building its Pennsylvania Station and electrified approaches, which were served by the PRR's lines in New Jersey and the Long Island Rail Road (LIRR). LIRR electric service began in 1905 on the Atlantic Branch from downtown Brooklyn past Jamaica, and in June 1910 on the branch to Long Island City, part of the main line to Penn Station. Penn Station opened September 8, 1910, for LIRR trains and November 27 for the PRR; trains of both railroads were powered by DC electricity from a third rail. PRR trains changed engines (electric to/from steam) at Manhattan Transfer; passengers could also transfer there to H&M trains to downtown Manhattan. On 
Title: New York, Philadelphia and Norfolk Railroad
Content:  Through the first half of the 20th century, several trains a day ran along the train line. From the 1920s to the 1950s, the PRR operated the day train, the Del-Mar-Va Express, and the night train, the Cavalier. At peak levels in the mid-1940s, the company also operated southbound, the Furlough, and an additional night train, the Mariner, in addition to unnamed local trains. Northbound the PRR added the Sailor, the Mariner night train, and an unnamed local train. By 1957 the named trains were gone, and all that remained was a once-a-day Philadelphia–Cape Charles train. In 1958, the route was shortened: from Philadelphia to Delmar, Delaware at the Delaware–Maryland border. The last train was a Wilmington–Delmar train, Blue Diamond, ending in 1965.
Title: SEPTA Regional Rail
Content:  The PRR and Reading operated both passenger and freight trains along their tracks in the Philadelphia region. Starting in 1915, both companies electrified their busiest lines to improve the efficiency of their passenger service. They used an overhead catenary trolley wire energized at 11,000 volts single-phase alternating current at 25 Hertz (Hz). The PRR electrified the Paoli line in 1915, the Chestnut Hill West line in 1918, and the Media/West Chester and Wilmington lines in 1928. Both railroads continued electrifying lines into the 1930s, replacing trains pulled by steam locomotives with electric multiple unit cars and locomotives. PRR electrification reached Trenton and Norristown in 1930. Reading began electrified 
Title: Pittsburgh and Lake Erie Railroad
Content:  rail service in 1971. P&LE operated commuter trains into Pittsburgh. In 1964, it ran one round-trip between Youngstown and Pittsburgh as well as one additional southbound and two additional northbound trains on the section between Beaver Falls and Pittsburgh. Latest by 1968, only the section between College Hill, Beaver Falls, Aliquippa and P&LE's Pittsburgh Terminal was served by one single roundtrip commuter train per day. In 1978, P&LE tried to drop that last commuter train, which was met by fierce objections. With state support, P&LE continued to operate the commuter run but eventually ended the service on July 12, 1985, after passenger counts had dropped significantly. The PATrain commuter operation continued to use some P&LE-trackage until 1989.
Title: Pennsylvania Station (1910–1963)
Content:  When Penn Station opened, it had a capacity of 144 trains per hour on its 21 tracks and 11 platforms. At the start of operations, there were 1,000 trains scheduled every weekday: of these, 600 were LIRR trains, while the other 400 were PRR trains. The commuting times of LIRR riders were cut by up to a half-hour. The station was so heavily used that the PRR soon added 51 trains to its daily schedule. The station also served New Haven trains to Westchester County and Connecticut after the Hell Gate Bridge opened in 1917. During half a century of operation, many intercity passenger trains arrived and departed daily to Chicago and 

Question: when did the prr first begin its passenger service between pittsburgh and philadelphia?
Answer: by 1854.
1854.