A polar vortex is set to bring cooler temperatures to a large swath of the country for the Thanksgiving holiday. The National Weather Services says it includes northern parts of the Pacific Northwest, the Great Plains, parts of Texas and the South, and the interior Mid-Atlantic. It comes as millions of Americans are set to hit the road for the holiday weekend. AAA estimates that nearly 82-million people will be traveling over the holiday, which is up two percent from last year.