Leavenworth is a city located in Leavenworth County Kansas. It is also the county seat of Leavenworth County. With a 2020 population of 35,627, it is the 12th largest city in Kansas and the 1108th largest city in the United States . Leavenworth is currently declining at a rate of -0.46% annually but its population has increased by 1.07% since the most recent census, which recorded a population of 35,251 in 2010. Leavenworth reached it's highest population of 38,495 in 1990. Spanning over 24 miles, Leavenworth has a population density of 1,470 people per square mile.
The average household income in Leavenworth is $75,819 with a poverty rate of 14.95%. The median rental costs in recent years comes to $958 per month, and the median house value is $123,800. The median age in Leavenworth is 35.1 years, 34.9 years for males, and 35.3 years for females.