Rise of big cities push Texas to swing-state territory -- maybe by 2020

This year, Democrats scored big wins in the fastest growing cities in Texas. The party won a dozen seats in the state House, mostly in clusters around Dallas and Houston. Forward Majority spent $2.2 million on those legislative races.

Voters in Harris County, where Houston sits, kicked out a three-term Republican county executive in favor of a 27-year old political neophyte. Nineteen black women ran for judgeships in Harris County; they all won.

Those gains in big cities came from a remarkable surge in turnout, and a realignment that shows just how solidly Democratic urban cores in Texas and around the nation have become.

In Harris County, Republicans won the straight-ticket vote by nine points in both 2010 and 2014. This year, Democrats outperformed Republicans in straight-ticket votes by 11 points.