[10] Although unnamed at the time,[11] Pennsylvania Avenue was designed in the L'Enfant plan as a critical thoroughfare for bringing existing roads into the heart of the new city.

[25] Benjamin Henry Latrobe, the architect newly hired to supervise the avenue's reconstruction, built three lanes separated by four rows of Black Poplars.

James Greenleaf, an early land speculator in the city, erected the first buildings, including six row houses, on Pennsylvania Avenue in the spring and summer of 1794 at the corner of Pennsylvania Avenue NW and 22nd Street NW, and another seven similar buildings were erected about the same time by Walter Stewart, a Continental Army general during the American Revolutionary War.

[40] The Baltimore and Ohio Railroad converted a house at the corner of 2nd Street NW and Pennsylvania Avenue into the city's first train station.

"[52][53][54] The two trapezoidal blocks sandwiched between Pennsylvania and Missouri Avenues (now the site of the National Gallery of Art) became home to such expensive brothels that it gained the nickname "Marble Alley.

[68][69] Spurred by the centennial of the transfer of the seat of government from Philadelphia to the District of Columbia, in 1900 the United States Congress formed the Senate Park Commission (also known as the McMillan Commission after its chair, Senator James McMillan) to reconcile competing visions for the development of Washington, D.C., and especially Pennsylvania Avenue, the National Mall, and nearby areas.

[82][90][91][92] The initial proposal, by architect Nathaniel A. Owings, envisioned a number of massive mixed-use buildings on the north side of Pennsylvania Avenue to complement Federal Triangle but which would also include theaters, restaurants, shops, condominiums, and apartments.

Mrs. Kennedy requested two things: That Cape Canaveral be renamed for her husband, and that the Pennsylvania Avenue redevelopment plan move forward.

[83][99][101] Johnson subsequently approved the establishment of a Temporary President's Commission on Pennsylvania Avenue (composed of Cabinet members, federal planners, architects, and others) to move the plan forward, although it did not hold its first meeting until May 21, 1965.

[93] The plan called for demolition of most of the existing structures north of Pennsylvania Avenue, but exercise of the government's powers of eminent domain would require (it was believed) creating a special designation for the area.

"Since its creation in the head of L'Enfant, from the time Jefferson planted Lombardy poplars along its edge, this has been the most important avenue in Washington," noted author Jeffrey F. Meyer.

"[109] Moynihan left public service (temporarily) in 1965, and Harry McPherson, counsel to President Johnson, kept the Pennsylvania Avenue redevelopment plan alive and shepherded it through additional revisions.

[110] Nonetheless, rejuvenation of Pennsylvania Avenue and the area north of the street began occurring as early as 1965, even though no permanent redevelopment authority had yet been established.

[111] The Brutalist style structure was designed by Edmund W. Dreyfuss & Associates, which worked closely with John Woodbridge (a staff architect for the President's Council on Pennsylvania Avenue and a member of the firm Skidmore, Owings and Merrill).

[118] Legislation to make the Temporary Commission permanent and give it extensive powers was introduced in October 1965,[119] but strong opposition to the proposed National Plaza emerged and hindered passage of the bill.

Faced with repeated threats to its existence and lower occupancy due to competition and anti-Vietnam War protests on Pennsylvania Avenue, the Willard Hotel closed suddenly on July 15, 1968.

[125] In October 1969, still stymied by the lack of movement on any redevelopment, the Temporary Commission agreed (at the urging of member Elwood R. Quesada, the President and chief executive officer of the L'Enfant Plaza Corporation) to seek $200 million in private financing to build several luxury apartment buildings on the north side of Pennsylvania Avenue.

[126] Moynihan, however, was now Counselor to the President for Urban Affairs in the Nixon administration in 1969, where he continued to provide leadership on the rejuvenation of Pennsylvania Avenue.

[127] President Nixon made a daytime walking tour of Pennsylvania Avenue on September 8, 1970, and expressed his support for the Moynihan plan.

[142] The Willard Hotel, Old Post Office Pavilion, and other historic buildings on Pennsylvania Avenue were retained and the underground expressway removed from the plan.

The National Park Service, chronically underfunded for the previous four decades, allowed the sidewalks, landscape plantings, and seating to deteriorate.

The newspaper cited "the crumbling infrastructure, the weak public spaces, and the imposing, secure federal presence" which makes Pennsylvania Avenue "a dead zone outside of lunch rush and the occasional march.

President James A. Garfield was shot in the Baltimore & Potomac Railroad Passenger Terminal on July 2, 1881, by Charles J. Guiteau; he died 79 days later on September 19.

[153] Prior to its designation as a historic site, six presidential funeral processions had traversed Pennsylvania Avenue, the last being President John F. Kennedy's in 1963.

[154] Admiral George Dewey, hero of the Battle of Manila Bay during the Spanish–American War, also led a parade up the avenue in 1899 after the United States' victory in that conflict.

[156] General John J. Pershing led the American Expeditionary Force in review up Pennsylvania Avenue in 1919 after the conclusion of World War I.

[165][166][167][168][169] When the "Bonus Army" was granted the right to march down Pennsylvania Avenue, it transformed the protestors in the eyes of most Americans from rabble-rousers to patriots seeking fairness.

[171] At 4:45 p.m., MacArthur led a battalion of infantry, a squadron of cavalry, and six battle tanks (commanded by Major George S. Patton) down Pennsylvania Avenue to remove the Bonus Army.

For example, in 1941 the labor and civil rights leader A. Philip Randolph proposed a march on Washington, D.C., by 100,000 African American men to pressure the United States government into establishing protections against discrimination.

[176] Roosevelt subsequently issued Executive Order 8802, which established the Fair Employment Practices Committee and banned discrimination in defense contracts.