Marathon is a city located in Florida. With a 2020 population of 8,623, it is the 179th largest city in Florida and the 3411th largest city in the United States. Marathon is currently declining at a rate of -0.13% annually but its population has increased by 3.93% since the most recent census, which recorded a population of 8,297 in 2010. Marathon reached it's highest population of 10,255 in 2000. Spanning over 9 miles, Marathon has a population density of 1,021 people per square mile.
The average household income in Marathon is $84,395 with a poverty rate of 14.29%. The median rental costs in recent years comes to $1,310 per month, and the median house value is $389,300. The median age in Marathon is 47.4 years, 46.7 years for males, and 47.7 years for females. For every 100 females there are 122.6 males.