Tioga County /taɪˈoʊɡə/ is a county in the U.S. state of New York. As of the 2020 census, the population was 48,455. Its county seat is Owego. Tioga County is part of the Binghamton metropolitan area.
 The county's name is a corruption of Iroquois De-yoh-ho-gah, meaning "at the forks" or "where it forks."
 As the number of residents increased in the region, in 1789 Montgomery County was reduced in size by the founding of Ontario County from some of its territory. The area taken from Montgomery County at that time was much larger than the present Ontario County, also including present-day Allegany, Cattaraugus, Chautauqua, Erie, Genesee, Livingston, Monroe, Niagara, Orleans, Steuben, Wyoming, Yates, and part of Schuyler and Wayne counties.
 In 1791 Tioga County was founded by another division of territory from Montgomery County (also founded then were Herkimer and Otsego counties. Tioga County was at this time much larger than the present county, including present-day Broome and Chemung counties and parts of Chenango and Schuyler counties.
 Tioga County was reduced in size in 1798 by the splitting-off of Chemung County (which also included part of the present Schuyler County and by the combination of a portion with a portion of Herkimer County to create Chenango County. In 1806 it was further reduced by the splitting-off of Broome County.
 According to the U.S. Census Bureau, the county has a total area of 523 square miles (1,350 km2), 519 square miles (1,340 km2) of which is land and 4.3 square miles (11 km2) (0.8%) of which is water.
 Tioga County is in southwest New York State, west of Binghamton and directly north of the border with Pennsylvania. The Susquehanna River flows into Pennsylvania from this county. The county is considered part of the Southern Tier region of New York State.
 The highest elevation is an unnamed 1,994-foot (608 m) hill in the county's northern corner. The lowest is 720 feet (220 m) on the state line where the Susquehanna flows into Pennsylvania.
 As of the census of 2010, there were 51,125 people living in the county, with 22,203 housing units, of these 20,350 (91.3%) occupied, 1,853 (8.3%) vacant. The population density was 98 inhabitants per square mile (38/km2). The racial makeup of the county was 96.9% White, 0.7% African American, 0.2% Native American, 0.7% Asian, 0.01% Pacific Islander, 0.3% from other races, and 1.1% from two or more races. Hispanic or Latino of any race were 1.4% of the population.
 As of the census of 2000, there were 51,784 people, 19,725 households, and 14,320 families living in the county. The population density was 100 inhabitants per square mile (39/km2). There were 21,410 housing units at an average density of 41 units per square mile (16/km2). The racial makeup of the county was 97.52% White, 0.54% African American, 0.22% Native American, 0.57% Asian, 0.01% Pacific Islander, 0.21% from other races, and 0.92% from two or more races. Hispanic or Latino of any race were 0.98% of the population. 16.6% were of German, 16.4% English, 14% Irish, 9.6% Italian, 5% Polish and 4% Dutch ancestry according to Census 2000. 96.9% spoke English and 1.6% Spanish as their first language.
 There were 19,725 households, out of which 34.70% had children under the age of 18 living with them, 58.70% were married couples living together, 9.80% had a female householder with no husband present, and 27.40% were non-families. 22.40% of all households were made up of individuals, and 9.40% had someone living alone who was 65 years of age or older. The average household size was 2.60 and the average family size was 3.04.
 In the county, the population was spread out, with 27.00% under the age of 18, 7.00% from 18 to 24, 28.80% from 25 to 44, 24.00% from 45 to 64, and 13.10% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 97.60 males. For every 100 females age 18 and over, there were 93.90 males.
 The median income for a household in the county was $40,266, and the median income for a family was $46,509. Males had a median income of $32,161 versus $23,653 for females. The per capita income for the county was $18,673. About 6.0% of families and 8.4% of the population were below the poverty line, including 10.0% of those under age 18 and 4.2% of those age 65 or over. There were 8,784 men of military age residing in the county.