I first discovered it on the official Winnipeg road map, which has all sorts of interesting quirks.

https://data.winnipeg.ca/City-Planning/Map-of-Road-Network/2eba-wm4h

I've tried to implement the fixes - something was very strange in that whole area. Please let me know if there's anything else that looks off.

"Main Street Bridge" is the official name, and is what appears on the Winnipeg road map at https://data.winnipeg.ca/City-Planning/Map-of-Road-Network/2eba-wm4h

"Bridge of the Old Forts" does appear on the local plaque, but "Main Street Bridge" is what it says on the street sign (the other bridge is signed as "Norwood Bridge").

Digging further, it looks like "Bridge of the Old Forts" was the previous 1931 bridge, but the current 1998 bridge is just "Main Street Bridge" https://pastforward.winnipeg.ca/digital/collection/berman/id/7719/

I'll defer to others on this, but it might be most accurate to call the bridge itself "Main Street Bridge" and have an historical marker for "Bridge of the Old Forts"?