The LaSalle St tunnel was in use until 1939, when it was closed because the Dearborn Subway (blue line) intersected its south ramp.

Rate this fact:

The north ramp of the tunnel is still open, but ends before the river at Carroll Ave.

Although the tunnel was built for pedestrian and horse-drawn traffic (in 1869), it was an important part of cable car traffic to the loop for almost 20 years.

There are some great old photographs of the tunnel, mostly from the south end, in "Chicago at the Turn of the Century in Photographs".