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The I-35W bridge over the Mississippi River in downtown Minneapolis will be bathed in red, white and blue on Monday in observance of Labor Day. The same colors will be used Friday to mark the 19th anniversary of the 9/11 terrorist attacks in which nearly 3,000 people were killed after airliners were purposely flown into the Pentagon in Washington, D.C., and the World Trade Center towers in New York City.

Later this month, the bridge will glow green for one night in honor of the Girl Scouts and on another night gold to bring attention to National Childhood Cancer Awareness month.

Carol Brant lives in a high rise overlooking the bridge and for years has watched the changing color displays. In a letter to the Star Tribune, she asked how the Minnesota Department of Transportation selects the colors and how they are displayed. Curious Minnesota, the newspaper's community-driven reporting project, is answering the question.

MnDOT lights the bridge for major holidays, for example, orange for Halloween, red and green for Christmas, and bright pink for Mother's Day. The agency also illiminates the bridge for special events such as this month's University of Minnesota Homecoming.

In 2016, the bridge glowed blue for 11 straight nights after the body of Jacob Wetterling was found 27 years after he was abducted at age 11 from near his home in St. Joseph, Minn. It also glowed purple after the death of music icon Prince. This summer, for the first time, the bridge was illuminated in changing colors to honor 2020 graduates. The MnDOT lighting schedule is available online.

In most cases, the bridge is lit up by request, said MnDOT lighting manager John Pedersen. MnDOT gets about 80 requests a year, including a one or two from couples getting married downtown who "want the bridge to match the color of the bridesmaid's dresses," Pedersen said.

MnDOT's policy is to accept requests only for nationally recognized events, and most, other than the wedding requests, are approved, he said.

When the new I-35W bridge was built to replace the old structure that collapsed on Aug .1, 2007, and left 13 people dead, it became one of the first segments of interstate highway in the country be illuminated with L.E.D. lighting. With more than 600 fixtures, "I can literally light the bridge with multimillions of colors," Pedersen said.

In Hennepin County, the arches on the Lowry Avenue bridge connecting north and northeast Minneapolis also are fitted with multicolored L.E.D. lights. The bridge will shine teal on Thursday to promote Ovarian Cancer Awareness Month, purple and gold Sept. 13 to recognize the Vikings' home opener, and red Sept. 15 in commemoration of World Lymphoma Awareness Day.

"Lighting of the Lowry Avenue bridge promotes the county, its civic institutions, state and federal holidays, and other public events of community significance," according to a county statement.

The county also accepts community requests, and sometimes lights it spontaneously as dictated by current events. The county recently lit the bridge purple in memory of Black actor Chadwick Boseman who died of cancer Aug. 28.

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