Buildings from the Revolutionary period are still preserved in the area. The state convention that ratified the Declaration of Independence met 1776 in White Plains, and in 1776, a principal rendezvous of the American Revolution followed General George Washington's retreat from New York City.

The Weckquaeskeck tribe, members of the Mohican nation, had lived on the land. They called their home Quarropas which was descriptive of the fogs that hung above the swamplands and remained suspended for days on end. Quarropas means the white marshes or the white plains. The land White Plains now occupies was first settled by New England colonists who bought it from the Mohican Indians in 1683. It has been a focal point in the history of New York State and the nation.

The White Plains Armory on South Broadway stands on the site of the original County Courthouse where, on July 11, 1776, the Declaration of Independence was read publicly in New York State for the first time. George Washington later established headquarters there, and the Battle of White Plains marked a turning point in the struggle for independence.

In 1778, White Plains became county seat of Westchester by legislative act. On April 3, 1866, White Plains became an incorporated village and in 1916, the Village was incorporated as a City.