Saratoga County is a county in the U. S. state of New York. As of the 2017 U. S. Census estimate, the county's population was 229,869, representing a 4. 7% increase from the 2010 population of 219,607, representing one of the fastest growth rates in the northeastern United States and the fastest-growing county in Upstate New York. The county seat is Ballston Spa. Saratoga County is included in the Capital District, encompassing the Albany-Schenectady-Troy, New York Metropolitan Statistical Area.