Waco Suspention Bridge. 2 January 2007. Photo: Georgi Petrov Waco (/ ˈ w eɪ k oʊ /) is a city in and the county seat of McLennan County, Texas.Situated along the Brazos River and on the I-35 corridor, halfway between Dallas and Austin, it is the economic, cultural, and academic center of the ‘Heart of Texas’ region.