Waco is a city which 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 US Census 2015 population estimate is 132,356. 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.