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Here’s a little-known fact for Chicago history buffs.

Chicago was the birthplace of National Clean Out Your Files Day. The April 22 event, first held in Chicago in 1995, has become a part of Earth Week, which starts Saturday.

Now, 95 cities observe Clean Out Your Files Day, on which offices around the country are supposed to clean out their files and recycle whatever they can.

In 1995, 3,500 employees at the Sears Tower tossed 27 tons of paper, said Ted Fischer, of the U.S. Conference of Mayors, which is sponsoring the event.

Mayor Richard Daley has planned a week of activities for the city.

Saturday: Drop off household hazardous waste at 1150 N. North Branch St. and receive a year’s supply of blue bags.

April 17: Recycle newspapers and magazines at various locations.

April 18: Donate unneeded eyeglasses at participating Chicago LensCrafters and Pearle Vision locations.

April 19: Learn home composition at Garfield Park Conservatory and other locations.

April 20: Donate old clothes at Salvation Army stores, the Caring Closet and other locations.

April 21: Donate old cell phones at Chicago police stations to help victims of domestic violence.

April 22: Clean out old files.

April 23: Recycle old batteries at all Chicago Public Library branches and Walgreen stores.