Waco is the county seat of McLennan County, Texas, United States. It is situated along the Brazos River and I-35, halfway between Dallas and Austin. The city had a 2010 population of 124,805, making it the 22nd-most populous city in the state. The 2020 population estimate for the city was 138,486. The Waco metropolitan statistical area consists of McLennan and Falls counties, which had a 2010 population of 234,906. Falls County was added to the Waco MSA in 2013. The 2020 U.S. census population estimate for the Waco metropolitan area was 277,005.