Ava is a city in northwest Jackson County, Illinois, United States. The population was 654 at the 2010 census.
Ava is located in northwestern Jackson County at 37°53′22″N 89°29′47″W (37.889346, -89.496355). Illinois Route 4 passes through the town as Knauer Street, leading northwest 15 miles (24 km) to Steeleville and east 10 miles (16 km) to its end at Illinois Route 13. Murphysboro, the county seat, is 14 miles (23 km) southeast of Ava.
According to the 2010 census, Ava has a total area of 1.069 square miles (2.77 km2), of which 1.06 square miles (2.75 km2) (or 99.16%) is land and 0.009 square miles (0.02 km2) (or 0.84%) is water.
As of the census of 2000, there were 662 people, 282 households, and 192 families residing in the city. The population density was 622.0 people per square mile (241.1/km²). There were 319 housing units at an average density of 299.7 per square mile (116.2/km²). The racial makeup of the city was 98.94% White, 0.30% Native American, 0.15% from other races, and 0.60% from two or more races. Hispanic or Latino of any race were 0.76% of the population.
There were 282 households out of which 31.9% had children under the age of 18 living with them, 55.0% were married couples living together, 8.9% had a female householder with no husband present, and 31.9% were non-families.