Sidney is a city located in Montana. With a 2020 population of 5,808, it is the 16th largest city in Montana and the 4366th largest city in the United States. Sidney is currently declining at a rate of -3.63% annually but its population has increased by 11.89% since the most recent census, which recorded a population of 5,191 in 2010. Sidney reached it's highest population of 6,825 in 2015. Spanning over 3 miles, Sidney has a population density of 1,766 people per square mile.
The average household income in Sidney is $76,784 with a poverty rate of 4.72%. The median rental costs in recent years comes to $819 per month, and the median house value is $213,000. The median age in Sidney is 35.8 years, 34.8 years for males, and 38 years for females. For every 100 females there are 99.4 males.