Which river is the largest in Texas?

• A. Rio Grande River
• B. Red River
• C. Colorado River
• D. Nueces River

Answer: (A)

Think about size in terms of length. The Rio Grande is the longest river that runs through Texas, stretching a long course from the mountains near New Mexico and Colorado down to the Gulf of Mexico and forming much of the Texas–Mexico border. That great length makes it the largest river among the ones listed. The Red River is shorter and mainly serves as a border with Oklahoma, the Texas portion of the Colorado River is substantial but shorter in overall length within the state, and the Nueces is much smaller and more limited in scope. So the Rio Grande stands out as the largest because of its extended path through Texas.