But when the big day finally arrives, just how old is the average Minnesotan getting married for the very first time? In 2021, the national median age of first marriage was about 29.2 years old (30.2 for men and 28.1 for women). USA Facts says the average age at which residents of the North Star State get married for the first time is 29.7 years old. That's slightly older than Wisconsin's first-married average age of 29.55, and nearly a year and a half older than the average age at which Iowans first get married, which is 28.45 years old. You can check the average first-married age in each of the 50 states below.