Seneca is a city located in Nemaha County Kansas. It is also the county seat of Nemaha County. With a 2020 population of 2,135, it is the 110th largest city in Kansas and the 7378th largest city in the United States . Seneca is currently growing at a rate of 1.43% annually and its population has increased by 7.23% since the most recent census, which recorded a population of 1,991 in 2010. Seneca reached it's highest population of 2,135 in 2021. Spanning over 2 miles, Seneca has a population density of 1,292 people per square mile.
The average household income in Seneca is $67,832 with a poverty rate of 7.19%. The median rental costs in recent years comes to $522 per month, and the median house value is $151,800. The median age in Seneca is 47.4 years, 43.1 years for males, and 51.4 years for females.