The evolution of Earth Day

    (AP file photo)

    (AP file photo)

    On Friday, a record 200 nations will mark the 46th anniversary of Earth Day. The United Nations will begin signing an international climate treaty on that day as well.

    Mike Weilbacher, executive director of the Schuylkill Center for Environmental Education, joined NewsWorks Tonight’s Dave Heller to look back at the event’s past and future.

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