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. Union has seen a significant amount of newer housing growth in recent years. Quite often, new home construction is the result of new residents moving in who are middle class or wealthier, attracted by jobs, a healthy local economy, or other amenities as they leave nearby or far away areas for greener pastures. 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 percentage of adults in Union who are college-educated is close to the national average for all communities of 21.84%: 20.94% of the adults in Union have a bachelor's degree or advanced degree.

The per capita income in Union in 2022 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.