This makes my knowledge feel less than complete

While viewing some footage of the flooding in central Texas, I discovered two items of knowledge that I am almost sheepish to admit I never knew before.

Item 1:  There is a river in Texas named the Colorado River.  Obviously, this is not the Colorado River that starts in Colorado and flows all the way to Mexico, passing through some remarkable erosional features along the way, which you likely have heard of.

Item 2:  The Colorado River of Texas is the longest river entirely in the state of Texas.  And it spans almost the entire state of Texas -- it's 862 mi (1,387 km) long.  For those who may be wondering, the Brazos River is longer but it starts in New Mexico.

Here's a map of the watershed of the Colorado River of Texas.