The city was established in 1948 but began to develop six years before it was granted the petition of incorporation. Charles F. Vatterott, the developer and builder of most of the residential and commercial properties in St. Ann, started the community as a housing project for families of workers employed in nearby defense plants. It was one of the few defense housing projects in the country to develop into a permanent town. The original homesite was dedicated in honor of Saint Ann, the mother of the Virgin Mary.
At the 2010 census there were 13,020 people, 5,894 households, and 3,259 families living in the city. The population density was. There were 6,496 housing units at an average density of. The racial makeup of the city was 69.5% White, 22.1% African American, 0.3% Native American, 2.2% Asian, 3.0% from other races, and 2.8% from two or more races. Hispanic or Latino of any race were 5.7%. Of the 5,894 households 28.3% had children under the age of 18 living with them, 31.6% were married couples living together, 17.9% had a female householder with no husband present, 5.8% had a male householder with no wife present, and 44.7% were non-families. 38.4% of households were one person and 12% were one person aged 65 or older. The average household size was 2.21 and the average family size was 2.93. The median age was 37.1 years. 22.4% of residents were under the age of 18; 9.2% were between the ages of 18 and 24; 28% were from 25 to 44; 27.4% were from 45 to 64; and 13% were 65 or older. The gender makeup of the city was 47.5% male and 52.5% female.
At the 2000 census there were 13,607 people, 6,190 households, and 3,447 families living in the city. The population density was 4,352.8 people per square mile. There were 6,554 housing units at an average density of 2,096.6 per square mile. The racial makeup of the city was 82.71% White, 11.44% African American, 0.28% Native American, 1.99% Asian, 0.01% Pacific Islander, 1.79% from other races, and 1.78% from two or more races. Hispanic or Latino of any race were 4.12%. Of the 6,190 households 25.8% had children under the age of 18 living with them, 37.4% were married couples living together, 14.3% had a female householder with no husband present, and 44.3% were non-families. 37.3% of households were one person and 13.2% were one person aged 65 or older. The average household size was 2.19 and the average family size was 2.90. The age distribution was 22.3% under the age of 18, 9.5% from 18 to 24, 31.8% from 25 to 44, 20.2% from 45 to 64, and 16.2% 65 or older. The median age was 37 years. For every 100 females, there were 93.5 males. For every 100 females age 18 and over, there were 87.8 males. The median household income was $32,351 and the median family income was $41,135. Males had a median income of $31,091 versus $24,064 for females. The per capita income for the city was $18,318. About 10.4% of families and 12.8% of the population were below the poverty line, including 19.0% of those under age 18 and 6.8% of those age 65 or over.
The St. Ann Police Department is responsible for law enforcement within the city. It is staffed with forty sworn full-time officers. The department has an active reserve program that contributes another dozen fully certified police officer to the force. The SAPD has a Special Response Team, a K-9 Unit, a Detective Bureau, School Resource Officers, and a DARE Officer. The Department maintains a Neighborhood Watch Program that meets monthly. St. Ann's dispatch center is responsible for dispatching units for St. Ann and the neighboring city of Edmundson. St. Ann also holds prisoners for Edmundson. The SAPD operates out of the St. Ann City Hall, located at 10405 St. Charles Rock Road, which also houses the city's municipal court and jail. The SAPD uses marked and unmarked Dodge Charger and Ford Police Utility vehicles. The chief is Aaron Jimenez, who was elected Chief of Police and Marshal Collector of the City of St. Ann in the 2013 municipal election. St. Ann is one of only a handful of St. Louis area municipalities which elects its police chief.
Business
, the largest enclosed shopping mall in Missouri, was located in St. Ann. However, the mall was closed in October 2010. At its peak, the mall contained 9 anchor stores and 210 smaller stores. Northwest Plaza was mostly demolished in 2013 to make way for the Crossings at Northwest a mixed-use retail and office project. Menard's Home Improvement Stores opened a 150,000SF store in August 2015, their 4th store in the St. Louis Metro Area at the Crossings. Charter Communications leased 135,000SF of an old Macy's Department Store and renovated it into a call center that will employ over a 1,000 employees.
Parks
The city's six parks are Tiemeyer, Livingston & Wright, Buder, St. Ann, Schafer and Mary Ridge. St. Ann also has a 34-par, 9-hole golf course on just outside St. Ann Park.
