On a recent Tuesday afternoon, 76-year-old Coi Serna and his 46-year-old daughter Gina Sustaita pulled up in her Toyota Highlander to the tin-roofed drive-thru at Oscar's Taco House for one of their ...

Flowing through sandstone bluffs, cottonwood bottoms, and wide floodplains, the Red River of the South winds hundreds of miles along the Texas-Oklahoma border before joining the Mississippi system.