Union is a somewhat small city located in the state of Missouri. With a population of 12,756 people and four associated neighborhoods, Union is the 68th largest community in Missouri. Much of the housing stock in Union was built relatively recently. The construction of new real estate can often be taken as an indication that the local Union economy is robust, and that jobs or other amenities are attracting an influx of new residents. This seems to be the case in Union, where the median household income is $68,864.00.

Also of interest is that Union has more people living here who work in computers and math than 95% of the places in the US.

The education level of Union citizens, measured as those with bachelor's degrees or advanced degrees, is similar to the national average for all American cities and towns. 20.94% of adults 25 and older in Union have a college degree.

The per capita income in Union in 2018 was $31,729, which is upper middle income relative to Missouri, and middle income relative to the rest of the US. This equates to an annual income of $126,916 for a family of four. However, Union contains both very wealthy and poor people as well.

Union is a somewhat ethnically-diverse city. The people who call Union home describe themselves as belonging to a variety of racial and ethnic groups. The greatest number of Union residents report their race to be White, followed by Black or African-American. Important ancestries of people in Union include German, Irish, English, European, and Italian.

The most common language spoken in Union is English. Other important languages spoken here include Polish and Other Indo-European.