Two sure signs of December in downtown Ann Arbor are the twinkle of white lights in the trees and packs of medical students clad in red ponchos and carrying buckets. The students are members of the Galens Medical Society, whose annual Tag Days have been a local institution since 1927.

That first year they collected $1,000 to provide a Christmas dinner for children spending the holidays at University Hospital. Last year, 175 volunteers raised $81,000 last year to support programs for young people across Washtenaw County.

Each donor receives a brightly colored tag that can be tied to the zipper of a winter coat. While the drive is underway, it can be next to impossible to navigate the city without running into a neighbor who’s been tagged. This year, the Galens will be out in force Thursday, December 5 through Saturday, December 7.