Monticello is a village located in the Town of Thompson in Sullivan County, New York, United States. The population was 6,512 at the 2000 census. It is the seat for the Town of Thompson and the county seat of Sullivan County. The village was named after the residence of Thomas Jefferson, but is pronounced as "mon-tah-sell-oh".
The Village of Monticello is in the central part of Thompson, adjacent to New York Route 17. Monticello is one of the largest villages in the county.
On March 20, 1801, an act was passed authorizing the building of a new turnpike road from the Hudson River to the Delaware through what was then Ulster and Orange counties. There were two important reasons for this undertaking. One was to facilitate travel between Newburgh and the rich coalfields of Pennsylvania and the other was to provide a suitable passage for large droves of cattle and wood products taken from the virgin forests of Sullivan County. The proposed Newburgh and Cochecton Turnpike ultimately brought about the founding of the village of Monticello.