Waterloo is a village in and the county seat of Seneca County, New York, United States. The population was 5,111 at the 2000 census and is now the most populated village in Seneca County. The village is named after the Waterloo in Belgium, where Napoleon was defeated.
The Village of Waterloo is mostly in the Town of Waterloo, but the part south of the Cayuga-Seneca Canal of the village is in the Town of Fayette and a small portion in the south-east corner of the village is in the Town of Seneca Falls. Waterloo is east of Geneva and is located in between the two main Finger Lakes, Seneca Lake and Cayuga Lake.
The area was within the realm of the Cayuga nation, one of several bands to form the Iroquois League. The current site of the village was the location of the former Cayuga village "Skoiyase" (or Skoi-Yase), meaning "flowing water", which was established around 1500. They were visited by Jesuit missionaries in the 17th Century. After the Sullivan Expedition of 1779 destroyed Skoiyase, many natives left the area. The land then became part of the Central New York Military Tract, reserved for veterans.
The first new settler, Jabez Gorham, arrived on the site of the village around 1795. The early village was known as "New Hudson". It was also known as "Scoys", based on the name of the former Indian village.
Because the original county seat in Ovid was deemed too close to the south county line after land was lost from Seneca County, Waterloo became the county seat in 1819. A similar fate befell Waterloo, when much of the north of Seneca County was lost, leaving the village close to the northern county line. The outcome was that both villages were made joint county seats, even though some of the lost towns were later returned to the county. Seneca County remains a two-shire county, although nearly all government activity now occurs in Waterloo. In honor of the two-shire history, the County Board of Supervisors will at least once a year hold a meeting in Ovid at the buildings locally called the "Three Bears".
Planning for the Women's Rights Convention in 1848 in Seneca Falls took place in Waterloo.
The Village of Waterloo was incorporated in 1824 and again in 1866, the same year it celebrated the first Memorial Day. Waterloo was officially designated as the official birthplace of Memorial Day in 1966 by President Lyndon B. Johnson; the Memorial Day Museum is in the town.