Okay, so it’s a re-enactment (you can tell with certainty by the photo of Lincoln on the stage–he has a beard, which Lincoln did not have until his presidency) but it’s a very long ago re-enactment!
Update: The Stephenson County Historical Society has now confirmed this photo is from the 1908 50th Anniversary celebration.
The Stephenson County Historical Society (1440 S Carroll Avenue, Freeport) provided the following information on Freeport, Illinois Lincoln-Douglas Debate re-enactments.
1903- President Roosevelt came and dedicated the monument
1908- 50th Anniversary
1915- 57th Anniversary (no one knows why there was a 57th but it seems there was!)
1929- Unveiling of the Lincoln the Debater statue
1958- Centennial celebration
2008- Sesquicentennial celebration
Neither Laura Keyes (Head of Adult & Technical Services, Freeport Public Library and Mary Todd Lincoln presenter) nor the Historical Society are 100 percent sure at which one this picture was taken, but it’s not likely 1903, because it doesn’t look like the other pictures Laura has seen of that year but it still could be. Her guess would be the 1908 or 1915.