The Mahicanni (Mahicans) dominated the area on the east bank of the Mahicanituck (Hudson River) in 1609 when Henry Hudson arrived. The Wappinger Confederacy was part of the Mahicanni (Mahican) nation and occupied Westchester and Putnam counties, the Bronx and Manhattan, the majority of Dutchess county and parts of Connecticut. Nathaniel Turner purchased parts of New Castle in 1640 from Ponas Sagamore, ruling chief of the Siwanoy. In 1661 John Richbell purchased a large tract of land including New Castle from Wappaquewam, who is rumored to be a Siwanoy, and in 1696 Caleb Heathcote purchased the same land again from Richbell's widow and the Sachems Wabetuck and Cohawney, who were supposedly Siwanoys.
In New Castle the Sint Sinks were located in the western part of the town, and the Tankiteke, in the eastern part, especially between the middle and towards the end of the 18th century. By the late 18th century their numbers had dwindled and they were completely gone from the area by 1791. Indian villages or sites include Chappaqua hill (between Quaker St and the railroad), the Sutton Reynolds farm, Wolf Hill Road, Roaring Brook, New Castle Corners, the Old VanTassel farm, "Coyemong" at Byram Lake, Wampus Lake, and near the Ossining border.
On April 5, 1791, New Castle held its first town meeting. Until then, it had been part of the Town of North Castle. The area had been settled earlier by Anglicans and Quakers. The Quakers came to "Shapequa" from Purchase and in 1753 built the Meeting House, which is the oldest documented building in New Castle and stands today. In 1776, following the Revolutionary War Battle of White Plains, the Meeting House provided shelter for some of General Washington's wounded. Residents from colonial times until the middle of the 19th century were largely self-sufficient farmers, part-time millers and craftsmen.
When the railroad came to Chappaqua in 1848 and to Millwood in 1869, the farms began to grow and ship "cash crops." To package and ship the cider, vinegar, apples, milk and other products, residents built cider mills, a pickle factory and a barrel factory. The two hamlets of Chappaqua and Millwood developed freight stations, livery stables, general stores and hotels. Later, 19th century industries included the Spencer Optical Works, near Mount Kisco, and the Bischoff Shoe Company in Chappaqua. Nevertheless, the Town remained a very small town, with 1,800 people in 1850 and less than 2,500 at the end of the century.
Gradually, the local industries lost their vitality, but the beauty of the land and the relative ease of transportation provided by the railroad remained and began to attract people who had accumulated wealth in New York City. Among these was Horace Greeley, who first bought land in Chappaqua in 1853, later owned the current "Horace Greeley House" and a large part of central Chappaqua.. Greeley was America's foremost newspaper editor, and an unsuccessful Presidential candidate, loosing to Grant in 1872. The wealthiest of the residents was probably banker Moses Taylor, whose estate included the land where the Mt. Kisco Country Club currently stands.
In 1902 the current Chappaqua railroad station (at left) was built. Millwood's first station was built in 1888 at a cost of $1,800. It burned soon after. For several years, the station was a baggage car. The present station was brought by flat car from Briarcliff Manor when Henry Law built and gave the Briarcliff station to the railroad in 1910.
In 1904, the Town's worst disaster, a tornado, swept down Quaker Street, stopping just short of the Quaker Meeting House. In 1912, Chappaqua put in a central water system. Following the World Wars, population of the town grew greatly. In the 1920's realtors promoted "the high pure air belt of Chappaqua." The Saw Mill River Parkway reached the Town in 1934 and in the late 30s and 40s lasting real estate developments took root. The most dramatic population increase came in the years following World War II. From 1950 to 1960 the number of people in New Castle rose by 60% to more than 14,000. A major factor in this increase was the acknowledged excellence of the Chappaqua school system. New Castle has been fortunate to retain much of its early charm - partly because of its vigorous terrain, and partly through the care given by owners, residents, and Town government to its historic building and areas.