They owned territory as far north as the Croton River.
His employees at Briarcliff Farms moved into the village, and the population grew to encourage Law to establish the area as a village.
In 1964 the new Village Hall opened, replacing the Municipal Building.
The present high school opened in 1971 to ease the large enrollment at the grade-school building.
Law's friend, Andrew Carnegie, called him "The Laird of Briarcliff Manor"; since the title appealed to all concerned, the village was named "Briarcliff Manor". It is conversationally called "Briarcliff", and often erroneously written as "Briar Cliff Manor" (although historically there has been little distinction).
The village has grown from 331 people when established to 7,867 in the 2010 census.
Briarcliff Manor was historically known for its wealthy estate-owning families, including the Vanderbilts, Astors, and Rockefellers. It has about 180 acres (70 ha) of recreational facilities and parks, all accessible to the public.
A proposition was presented to the supervisors of Mount Pleasant and Ossining on October 8, 1902 that the area of 640 acres with a population of 331 be incorporated as the Village of Briarcliff Manor, The Tudor Revival-style Briarcliff Lodge was opened in 1902 as a premier resort hotel.
It was surrounded by Walter Law's dairy barns and greenhouses, and hosted numerous distinguished guests, including Franklin and Eleanor Roosevelt.