Sibley is a city located in Osceola County Iowa. It is also the county seat of Osceola County. With a 2020 population of 2,508, it is the 135th largest city in Iowa and the 6819th largest city in the United States . Sibley is currently declining at a rate of -1.30% annually and its population has decreased by -10.36% since the most recent census, which recorded a population of 2,798 in 2010. Sibley reached it's highest population of in . Spanning over 2 miles, Sibley has a population density of 1,491 people per square mile.
The average household income in Sibley is $70,682 with a poverty rate of 12.99%. The median rental costs in recent years comes to $654 per month, and the median house value is $78,100. The median age in Sibley is 41.9 years, 36.6 years for males, and 46.9 years for females.