The traffic circle at the intersection of Massachusetts, Connecticut, New Hampshire, P, and 19th Streets was part of Pierre L'Enfant's original 1791 plan for Washington but was not actually built until 1871, when the Army Corps of Engineers laid out the roundabout. It was called Pacific Circle then, because it sat at the western edge of the city's residential development. In February 1882 Congress renamed it for Rear Admiral Samuel Francis Du Pont and authorized a memorial bronze statue, dedicated in 1884. The statue was replaced in 1921 by the current double-tiered marble fountain designed by Henry Bacon and Daniel Chester French, the team responsible for the Lincoln Memorial. The fountain has stood at the center ever since.

Between the 1870s and 1900 the broad diagonal avenues converging on Dupont Circle filled with the kind of palatial mansions that Gilded Age fortunes bought. Stewart's Castle, an 1873 confection on the north side, was demolished long ago. The James G. Blaine Mansion of 1882 still stands on the west side. The Patterson Mansion at 15 Dupont Circle, designed in 1901 by Stanford White for Chicago Tribune editor Robert Patterson, is the only one of the original ring of grand houses still in residential use. In 1927 the Coolidges lived there for several months while the White House underwent repairs, and welcomed Charles Lindbergh as a houseguest after his transatlantic flight. The Patterson House also became the launching pad for Cissy Patterson's combative ownership of the Washington Times-Herald, which she used through the 1940s to attack Franklin Roosevelt and promote isolationism in concert with her brother Joseph at the New York Daily News and her cousin Robert McCormick at the Chicago Tribune.

The neighborhood west of 16th Street, between Swann Street and Florida Avenue, became known in the late nineteenth century as Strivers' Section. A turn-of-the-century Black writer described the area as a community of Negro aristocracy, and the name stuck. Frederick Douglass owned a row of houses on 17th Street that his son occupied. Strivers' Section was where upper-middle-class African American Washington put down roots during the long decades when much of the rest of the District was rigidly segregated. The area is now its own historic district. Many of the original Edwardian rowhouses survive, alongside a handful of early apartment buildings, and the neighborhood retains a quieter, more residential character than the commercial core around the circle.

After World War II and especially after the 1968 riots, Dupont declined. Wealth had been moving to the Maryland and Virginia suburbs for decades, and the postwar shift accelerated. Many of the Massachusetts Avenue mansions were divided into apartments or sold to embassies. The neighborhood became cheaper than its location and architecture should have allowed, which made it attractive to the urban pioneers who moved in during the 1970s: artists, students, gay men and lesbians, immigrants, anyone trying to live in the city differently than the suburbs were offering. The 19th Street commercial strip and the surrounding rowhouses became the center of one of America's most established gay neighborhoods through the 1970s and 1980s. The annual High Heel Race down 17th Street, run every Tuesday before Halloween since 1986, still draws thousands of spectators.

The streetcar underpass beneath Dupont Circle, built in 1949 to carry trams on Connecticut Avenue under the traffic on Massachusetts, was closed in 1962 when the District's streetcar system was shut down. The tunnels sat empty for decades before being reopened as the Dupont Underground arts space in the 2010s. Above ground, the circle today is a counterclockwise outer ring serving the intersecting streets and an inner ring for Massachusetts Avenue through-traffic. The central park is maintained by the National Park Service. The fountain still flows. The benches and the grass around it host political rallies, weekend chess games, drag queens, lobbyists, and homeless veterans. In 1999 a woman named Thelma Billy was arrested for handing out Thanksgiving dinner to people sleeping in the park, an incident that briefly became a national news story. The Sunday farmers' market on 20th Street has been going since 1997. Coffeehouses, restaurants, and upscale retail have replaced most of the bookstores, but the circle remains what it has been since at least the 1970s: one of the few corners of central Washington that feels lived in rather than merely worked in.