Pennsylvania Avenue National Historic Site influenced by L'Enfant Plan
History of the site
Construction of Pennsylvania Avenue
Prior to the settlement of the area by European colonists, the Piscataway tribe of Native Americans occupied the northeastern banks of the Potomac River, although no permanent settlements are known in the area now encompassed by the city of Washington.  As the region began to be settled, David Burnes obtained the first title to the area which would become Pennsylvania Avenue NW in 1774.Article One, Section 8, of the United States Constitution established a "District... [to] become the seat of the government of the United States..." The Residence Act of 1790 (as amended), established this district and gave to the President of the United States the authority to fix the location of the site somewhere along the Potomac River. President George Washington chose the current site of the city in 1791, and it was surveyed later that year. At the time, it was not foreseen that the city of Washington would be coterminous with the District of Columbia, and Washington set the northern boundary of the city roughly where Pennsylvania Avenue is today. Washington chose Pierre (Peter) Charles L'Enfant to plan the new city. Although unnamed at the time, Pennsylvania Avenue was designed in the L'Enfant plan as a critical thoroughfare for bringing existing roads into the heart of the new city. It was also designed to link the "president's palace" with the Capitol building planned for Jenkin's Hill (now Capitol Hill).Pennsylvania Avenue was created on April 14, 1792, when the three commissioners then overseeing the District of Columbia ordered "the middle of the avenue from the president's palace to the capitol" cleared. The origin of the name "Pennsylvania Avenue" is somewhat obscure.  The name was first applied to the avenue in a letter from surveyor and map-maker Benjamin Ellicott to the District's commissioners in December 1791.The actual clearing of Pennsylvania Avenue did not begin until spring 1796. Much of Pennsylvania Avenue below 9th Street was swampy and nearly unusable, as Tiber Creek curved north to border the avenue at 9th Street and again at 5th and 4th Streets before actually crossing it at 2nd Street. The damp earned the street the nickname of the "Great Serbonian Bog." (This marshy area was filled in and dried beginning in 1816.) In the fall of 1800, Pennsylvania Avenue was cleared of underbrush, and a 6-foot-wide (1.8 m) raised footpath covered in stone chips was built. A stone bridge over Tiber Creek at 2nd Street was also built during this time, being replaced by a brick arch in 1817. On March 3, 1803, President Thomas Jefferson ordered that Pennsylvania Avenue be widened and the road completed. Benjamin Henry Latrobe, the architect newly hired to supervise the avenue's reconstruction, built three lanes separated by four rows of Black Poplars.Additional improvements to the street were made throughout the 19th century: The avenue was macadamized in 1832 (and the poplars removed), repaved with round stones in 1852, and repaved with wooden blocks from 1st to 15th Streets in 1870. The wooden blocks required such extensive repair, however, that between 1876 and 1877 they were replaced with rock from 1st to 6th Streets NW, and with grahamite asphalt from 6th to 15th Streets NW. The avenue was repaved in 1890 and again in 1907.