Motorists cruising through Minneapolis March 8 noticed the bright orange glow of the Lowry Avenue Bridge. And most would have thought the color scheme was just a random choice.

But the hue selection was specifically requested by an organization for Multiple Sclerosis Awareness Day to jump-start discussion about the disease.

Since the bridge, which crosses the Mississippi River, reopened in 2012, more than 100 groups have applied to Hennepin County to have their cause or important day highlighted with special lighting. The most recent was Thursday, when the bridge was lighted green for National Children’s Mental Health Awareness Day.

“It’s an opportunity to take some action and make something happen,” said Holly Anderson, president of the Upper Midwest Multiple Sclerosis Society. “It becomes a connection point for people.”

When the bridge reopened, the County Board passed a resolution to allow the public to apply for special lighting to commemorate or enhance a specific cause at no charge. Events such as birthdays, anniversaries or private events are excluded. The bridge is equipped with multicolor LED lighting options to illuminate the arches.

All the major holidays are represented with lighting — The 4th of July is of course red, white and blue. The state’s professional teams often are honored with a day, and Prince’s death received a purple tribute.

Some of the groups and causes that have requested lighting include the Salvation Army, Twin Cities Pride festival, infant loss and remembrance, hunger awareness, organ donation and law enforcement. The Star Tribune is also getting into the act with a green bridge for the paper’s 150th anniversary on May 25.

The special lighting remains in place from 6 p.m. to 6 a.m. County administration approves requests, which need to be made 14 days before the date would be lighted. The demand increases each year, and “nothing controversial” has had to be turned down, said Melissa Booth, who works for county administration.

“We don’t market the special dates beyond a listing on the county website,” she said. “This has been really successful and positive for the community.”

The MS Society has lit up the Lowry Bridge, along with the I-35W Bridge and some downtown buildings, for several years. People flock to the sites, taking pictures and posting them on social media, Anderson said. “Then it goes all over the place,” she said. “It brings more people into our movement.”

Beyond public awareness, the bridge lighting coincides with donation activities and legislative initiatives. The symbol can also be a powerful force to connect people with the lifetime disease, which can be particularly important with multiple sclerosis because people are generally diagnosed later in life, Anderson said.

In April, Wendy Vossen of the Comfort The Center for Autism asked that the Lowry and I-35W bridges be royal blue as part of World Autism Day. It knows the action had an impact on starting conversations about autism.

“The bridge was an important event for us to celebrate where we came from being with autism, where we are now and where we are going,” she said. “We hoping it gets bigger and better every year.”