Spencer is a city located in Clay County Iowa. It is also the county seat of Clay County. With a 2020 population of 10,834, it is the 35th largest city in Iowa and the 2934th largest city in the United States . Spencer is currently declining at a rate of -0.54% annually and its population has decreased by -3.55% since the most recent census, which recorded a population of 11,233 in 2010. Spencer reached it's highest population of 11,726 in 1980. Spanning over 11 miles, Spencer has a population density of 991 people per square mile.
The average household income in Spencer is $61,108 with a poverty rate of 12.11%. The median rental costs in recent years comes to $684 per month, and the median house value is $128,800. The median age in Spencer is 43.5 years, 42.4 years for males, and 44.5 years for females.