Jefferson Valley is located in Yorktown, NY in Westchester County. The town is named after the Battle of Yorktown, which was near Yorktown, Virginia. The town of Yorktown has a splendid historical heritage beginning with the earliest known inhabitants: Mohegan, Osceola, Amwalk, Kitchawan and Mohansic, which are all familiar names of local places. The Mohegans of the Algonquin Nation had habitations within the boundary of Yorktown.

Historically, the area known as Jefferson Valley, in addition to the village proper, included a large portion of northeastern Yorktown, comprised of all the farms on Wood Street and Route 6N, north of the Putnam county border, all those on Old Route 6 (Main Street) and Old Jefferson Valley Road, from the Somers line in the east, to about the present location of Lee Road in the west; and also, all the farms along Gomer Street, south to Cording Road.

The valley itself is defined principally by Indian Hill on the north, with its highest elevation of 751 feet and on the south by the hills which Gomer and Quinlan Streets traverse. (It is to be noted that what is meant here as Gomer Street is the road before 1965, more of which shall be spoken on further.) As one would expect, these hills afford magnificent views, the most accessible of which is the one from Quinlan Street. From there one can see Bear Mountain, the Highlands, Carmel and even the foothills of the Berkshires.

At the foot of Indian Hill lies Lake Osceola. A glacial remnant of the last ice age, it once formed part of a large lake which stretched westward to Mohegan. Prior to its present name, which it had acquired by the 1880's, Lake Osceola had borne several other designations, including "Round Pond" and "Jefferson Pond."