White Plains is a city in Westchester County, New York, United States. As of the 2000 census, the city had a total population of 53,077, but a July 1, 2002 Census estimate put the city's population at 55,394. It is the county seat of Westchester County^GR6.

Sometimes referred to as the "WP," White Plains is perhaps the most significant of the edge cities that have developed outside of New York City. While the city itself dates to the colonial period, since the mid-1980s it has experienced a tremendous commercial and residential boom. By the late 1990s and Early 2000s, many major corporations that had headquarters in New York City ended up moving to White Plains. The construction of the Galleria at White Plains ushered in a period of new construction downtown and on the Westchester Avenue (NY Route 119) corridor, including a series of skyscrapers, department stores and apartments. In the past ten years, development has continued as the city has become the leading retail and office center in Westchester County. A new courthouse for the Southern District of New York opened in 1998. An infusion of immigrants (largely from Mexico) and urban professionals drawn by the city's close commuting distance to midtown Manhattan (30 minutes by express train) has lent White Plains a cosmopolitan air in recent years.

The city's permanent population has experienced a growth spurt since 2000 as a number of high-end apartment towers have been constructed. The City Center development, opened in 2004, features two skyscrapers, One City Place and Trump Tower above 600,000 square feet of retail, restaurant and entertainment space with commanding views of the lower Hudson Valley. The project also provided White Plains with some of the most prestigious addresses in Westchester County.

In 2005, construction of The Renaissance Square and Ritz-Carlton, Westchester began. The project will feature a 123 room Rtiz-Carlton Hotel and more than 400 private condominiums in downtown White Plains at the intersection of Main Street and Mamaroneck Avenue. Housed within two 40-story towers, the hotel and residences will be a landmark structure, designed by the architectural firm of Costas Kondylis and Partners of New York City, with interiors by renowned designer Frank Nicholson. The expected opening date of the first tower is early 2008. The second tower will include nearly 11,000 square feet of street-level retail/restaurant space as well as open space that will help tie together the heart of the downtown. It will also have a four-level 1,000-space parking garage. The final layout for the tower is pending and will be built as phase two of the construction.

In large part because of its proximity to New York, the cost of living in White Plains has been ranked as second most expensive in the nation (to New York City).

White Plains is home to one of the campuses of Pace University, as well as the White Plains campuses of Mercy College and Berkeley College. The city boasts two Metro North commuter railroad stations, White Plains and North White Plains. White Plains is also the home of fast-growing Westchester County Airport, an international transportation hub which offers regional travelers an alternative to New York's congested three major airports.

In 1956, Marilyn Monroe married Arthur Miller in a civil ceremony in White Plains.

During the American Revolutionary War, the Battle of White Plains took place on Chatterton Hill, located just west of the downtown area on the Bronx River Parkway.