Posen is located at . According to the 2010 census, Posen has a total area of, all land.
History
The area that is now Posen was settled by farmers, mainly of Dutch and German origin, in the second half of the 19th century. In 1893 a Chicago-based real estate firm hired 75 agents in the Polish-speaking areas of Germany to sell land to Poles seeking to emigrate to the United States. Over the next few years the village emerged as a place largely inhabited by factory workers, mainly employed at nearby Harvey, who also had room on their lots for gardens. In 1894 the Roman Catholic Archdiocese of Chicago established a mission to serve the Polish residents of Posen, which was elevated to parish status as St. Stanislaus the Martyr in 1898. In the 1930s the population of Posen was 98% of Polish origin, and in 1960 only 0.1% of the population was identified in the census as being not white, or 4 of the 4,513 inhabitants. In 1963 there were 7% black students that attended the Posen School. In 1990 Posen, having fallen to 4,226 inhabitants, was still 94.5% white, a large portion of this population being Polish. About 4% of the population identified as being both white and Hispanic, for an overall 7.3% or 310 people identifying as being Hispanic. In 2010 3,171 residents of Posen identified as Hispanic, representing the expansion of the Hispanic population to 10 times what it had been 20 years before. In the same time period the number of African American residents of the village increased from 60 to 1,035. This means that the percentage rate of growth of the African American population of Posen over the last 20 years has been greater than that of the Hispanic population. While as late as 2004 the Encyclopedia of Chicago still referred to Posen as "predominantly Polish American" even then an actual examination of the 2000 census ancestry report would have shown that only a quarter of the population claimed to have Polish ancestry.
Demographics
As of the 2010 census, there were 5,987 people, 1,765 households, and 1,383 families residing in the village. The population density was 5,117.1 people per square mile. There were 1,883 housing units at an average density of 1,609.4 per square mile. The racial makeup of the population was 57.0% white, 17.3% black, 0.6% Native American, 0.4% Asian, 0.1% Pacific Islander, 20.9% reporting some other race and 3.7% reporting two or more races. 53.0% of the population was Hispanic or Latino of any race, including the 50.5% of the population that identified as being ethnically Mexican. Estimates of ancestries for the period 2007-2011 put the Polish percentage in Posen at around 7.9% of the population. There were 1,765 households, out of which 50.0% had children under the age of 18 living with them, 52.2% were headed by married couplesliving together, 17.1% had a female householder with no husband present, and 21.6% were non-families. 16.8% of all households were made up of individuals, and 5.9% were someone living alone who was 65 years of age or older. The average household size was 3.39, and the average family size was 3.81. In the village, the population was spread out with 31.5% under the age of 18, 10.3% from 18 to 24, 29.7% from 25 to 44, 21.2% from 45 to 64, and 7.2% who were 65 years of age or older. The median age was 30.8 years. For every 100 females, there were 102.2 males. For every 100 females age 18 and over, there were 99.1 males. For the period 2007-11, the estimated median annual income for a household in the village was $52,724, and the median income for a family was $53,311. Male full-time workers had a median income of $37,278 versus $30,380 for females. The per capita income for the village was $15,944. About 14.7% of families and 14.0% of the population were below the poverty line, including 17.3% of those under age 18 and 15.3% of those age 65 or over.
