The high bluff of Mount Forest Island overlooking this critical location has served as a lookout for centuries.

The French fort on the site was visited by Father Jacques Marquette on his journeys on the Des Plaines River several times in 1673.

Rock quarries developed there in the mid-19th century due to the combination of an abundant supply of quality stone, and convenient transportation on the nearby canal.

Though the quarries themselves no longer operate, businesses selling stone products continue in the Sag Bridge area today.

On March 27, 1991, a tornado caused significant damage to Lemont and Sag Bridge, including the historic St. James Church and cemetery.