Willis, TX has a population of 6,217 and is the 5,622nd largest city in the United States. The population density is 1,314 per sq mi which is 1255% higher than the Texas average and 1350% higher than the national average. The median age in Willis is 26 which is approximately 24% lower than the Texas average of 34. In Willis, 53% of the population over 15 years of age are married, 67% speak English and 33% speak Spanish. 62% of Willis residents were born in Texas, 24% were born out of state, 1% were born outside of the United States and 14% were foreign born.