Colfax, IL has a population of 1,081 and is the 14,652nd largest city in the United States. The population density is 1,967 per sq mi which is 785% higher than the Illinois average and 2071% higher than the national average. The median age in Colfax is 41 which is approximately 9% higher than the Illinois average of 37. In Colfax, 65% of the population over 15 years of age are married, 98% speak English and 0% speak Spanish. 79% of Colfax residents were born in Illinois, 20% were born out of state, 0% were born outside of the United States and 1% were foreign born.