BROOKLYN, Mich. (AP) — Michigan residents are marking the 15th anniversary of 9/11 with memorial services, mobile exhibits and a big blood drive at a racetrack.

More than 550 people visited the Michigan International Speedway in Brooklyn on Sunday to donate blood for the Spirit of America drive. The Jackson Citizen Patriot reports participants could ride a tram around the track and pass a field of flags representing lives lost.

WOOD-TV reports Grand Valley State University students organized a memorial including 2,977 mini-U.S. flags at its two western Michigan campuses.

The “9/11 Never Forget Mobile Exhibit” is being displayed at the Gerald R. Ford Presidential Museum in Grand Rapids.

Nearly 3,000 people died when hijacked planes slammed into the World Trade Center, the Pentagon and a field near Shanksville, Pennsylvania, on Sept. 11, 2001.