Buffalo, IA has a population of 1,226 and is the 13,906th largest city in the United States. The population density is 181 per sq mi which is 232% higher than the Iowa average and 100% higher than the national average. The median age in Buffalo is 40 which is approximately 5% higher than the Iowa average of 38. In Buffalo, 59% of the population over 15 years of age are married, 99% speak English and 1% speak Spanish. 70% of Buffalo residents were born in Iowa, 28% were born out of state, 0% were born outside of the United States and 3% were foreign born.