[4] 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 (the church permanently closed in 2022).

In 1990 Posen, having fallen to 4,226 inhabitants, was still 94.5% white, a large portion of this population being Polish.

In the same time period the number of African American residents of the village increased from 60 (or 1.4% of the population) to 1,035.

[12] The Roman Catholic Archdiocese of Chicago operated St. Stanislaus Bishop and Martyr School in Posen from its opening circa 1893 until it closed in 2006.

[13] Pace provides bus service on routes 349, 354 and 359 connecting Posen to destinations across the Southland.