Greer is a city in the Greenville and Spartanburg counties in the U.S. state of South Carolina. As of the 2020 census, the population was 35,308…Greer is a city in the Greenville and Spartanburg counties in the U.S. state of South Carolina. As of the 2020 census, the population was 35,308, making it the 14th-most populous city in South Carolina. Greer is included in the Greenville-Anderson-Greer, SC Metropolitan Statistical Area, which is part of the Greenville-Spartanburg-Anderson, SC Combined Statistical Area in Upstate South Carolina.