The county office building is located at 1 DiPronio Drive, Waterloo NY 13165; phone: 315‑539‑1800.
The governmental seat of Seneca County was established at Ovid Village, also called Verona, upon the organization of the county in March, 1804. A frame courthouse was erected in 1804 upon the site now occupied by the courthouse complex buildings. However, the formation of Tompkins County in 1817 from surrounding lands including parts of southern Seneca County placed Waterloo and not Ovid in the geographic center of the county and a new courthouse was established in that community soon after. In 1819, the State Legislature, acting on a petition from Ovid citizens, returned a portion of the recently created Tompkins County to Seneca County. The formation of Wayne County to the north in 1823 removed further land area from Seneca County and placed Waterloo and Ovid equally distant from the geographic center of the county. Therefore, the State Legislature compromised and in that year designated both towns as "half shire" seats of county government in alternating terms of three years each.