Haute-Garonne is a department in the southwestern French region of Occitanie. Named after the river Garonne, which flows through the de…Haute-Garonne is a department in the southwestern French region of Occitanie. Named after the river Garonne, which flows through the department. Its prefecture and main city is Toulouse, the country's fourth-largest. In 2019, it had a population of 1,400,039.