Mark P. Jones, the Baker Institute’s fellow in political science as well as the Joseph D. Jamail Chair in Latin American Studies and chair of the Department of Political Science at Rice University, has ranked the ideological composition of registered voters in Texas' 20 most populous counties using University of Texas/Texas Tribune Polling Data. His explanation and write-up can be found in the Baker Institute Blog at the Houston Chronicle.
Jones' analysis follows on an earlier piece in the Texas Tribune's TribTalk about how "how the liberal outlier status of Travis County" provides part of the context for the recent indictment of Governor Perry by a Travis County grand jury.
The data sets Jones uses are all available with other related resources at our polling data archive.