Unit 1 construction begins on the IMU and building plans arise from a three-acre barn plot. The first phase of the IMU includes the Main Lounge offices, and a snack bar.

The IMU was one of 16 college union buildings in the U.S. in 1925 and assumed the role as a service center on campus, offering Union Dining Service, housing and employment services and the Union Browsing Library.

Unit II construction is completed and dedicated. Union activities involve games, dances, UI Band concerts, and homecoming. Additions include a radio broadcast room, soda fountain, and roof deck.

During the 1930s, the IMU transitions its focus to entertainment and the arts. The Silver Shadow, a non-alcoholic nightclub, opens within the Union Cafeteria and the Class of 1935 establishes a fund for the Mark Twain room.

IMU Corporation Board of Trustees gifts the IMU to the University of Iowa. The facility is used by the U.S. Army, during WWII to feed and train cadets.

The IMU hosts a celebration for the centennial birthday of the University.

Unit III construction is completed featuring billiards, bowling, snack bar, student lounges, and music rooms.

During the 1960s, the IMU serves as a platform for student activism, demonstration, and entertainment. In 1964, the Soapbox Soundoff begins as a stage for political commentary and the Thieves Market holds its first student art exhibition.

In the 1970s, students and faculty from the art and music departments use the IMU as a creative, collaborative space.

In 1976, the University of Iowa Lecture Committee hosts best-selling author Maya Angelou in the IMU Main Lounge.

The 1988 renovation links the 1920s and 1955 additions of the building; adding the Terrace Lobby entrance on Madison street, Student Activities Center, and the University Bookstore.

In the 1990s students continue to use the IMU as a center for entertainment, food, and relaxation between classes.

The IMU's University Box Office sold tickets to the latest firms, student organization events, movies, and campus concerts.

The IMU hosted academic, social, and multicultural events during the early 2000s. Events included a discussion with Gloria Steinem, a speech by Angela Davis, and each February, UI Dance Marathon.

The Iowa Flood of 2008 devastated the UI campus and closed the IMU from June through November. The building required an extensive flood mitigation process.

The campus community enjoyed a variety of entertainment including, comedy, concerts, and fireworks!

The IMU Flood Recovery and mitigation project is completed. The ground floor and new IMU River Terrace open to the public.

The IMU remains an incubator for student ideas, programs, and initiatives for all students. In 2018 it became home to the Food Pantry, Clothing Closet, and Collegiate Recovery Program.