As Saint Paul’s population grew in the late 19th Century, people began moving out of the city’s core and into residential areas adjacent to downtown. The Selby Avenue streetcar line was built in 1888 to provide people with transportation from their homes on top of the hill to the offices, factories, and shops downtown, and to the transportation hub – Union Depot. With the newly christened Selby-Lake line up and running, the streetcars made runs between Minneapolis and St. Paul at all times of the day. The Selby-Lake line was the most popular route in the entire streetcar system.
Most of the line traversed a flat Twin Cites landscape. Near the Cathedral of Saint Paul the electric engines of the streetcars struggled to climb the steep 14 percent grade. The system used counterweighted cable cars but a more permanent solution had to be found as service up and down the hill was slow and dangerous. The cable cars could not travel more than 10 miles per hour.
In 1906 the Twin Cities Rapid Transit (TCRT) cut a tunnel under Selby Avenue lowering the grade to 7 percent, which was manageable for the electric streetcars to handle without counterweights. After a year of digging, the two-track tunnel opened in 1907. Streetcars bound for downtown St. Paul travelled below this section of Selby Avenue near Nina Street and descended quickly through the 1,472 -foot long passage to emerge at the base of the hill.
Businesses quickly sprung up along the Selby line that catered to people’s basic needs. Grocers, butchers, confectioneries, cobblers, movie houses, pharmacies, tailors, and dressmakers all lined the corridor. The corner of Selby and Dale was the hub; at one time there were twenty-six businesses on a single block. By the peak of streetcar commerce in 1930, nearly one hundred businesses aligned on Selby Avenue between Western and Lexington Parkway. By the end of World War II, the streetcar system ridership began to decline.
The last streetcar passed through the tunnel in 1954, three years after General Motors promised to finance 525 city busses, with the understanding that all streetcars would be taken off the streets and the rails would be sold or destroyed. Today, the lower entrance to the tunnel can still be seen below the Cathedral of St. Paul, complete with tracks appearing from a thick concrete wall that blocks anyone from going inside.

An excerpt from Minneapolis-Saint Paul: Then and Now showing the pre-tunnel streetcar tracks, and the area over the tunnel as it is today.
I wish they would pave the ROW and open it up to cyclists and pedestrians. I bike commute into downtown St. Paul, and every single option for getting in/out of downtown sucks.
A couple of facts need correcting. The cable car line on Selby opened in 1887. It was electrified in 1898 and extended only as far west as Prior Avenue. The line on Lake Street opened in 1905. In 1906 it was extended across the Mississippi to form the intercity Selby-Lake line. Streetcars were replaced by buses in 1953.
Thanks Aaron! When it was electrified, did the cable go away? Or was it still needed for the hill?
The cable stayed at first, though an elaborate counterweight system was used. The regular streetcars were pushed up the hill and led down the hill by dedicated special cars which had the facility to clamp onto the cable. Once the tunnel was created the cable system was removed. Aaron or I could probably dig out some diagrams of the cable/counterweight system if there was sufficient interest.
Any chance the loading gauge of this tunnel is compatible with our METRO light rail vehicles? See where I’m going with this?
It seems to my eye to be a smol tunnel but it should be re-opened for bikes and pedestrians.
When the line was electrified in 1898, a counterweight cable system was installed to assist streetcars up and down the 16% grade below the cathedral. The tunnel replaced it in 1907, lowering the grade to 7%.
And yes, I think the tunnel would accommodate light rail cars.
Wonder where you got that great pic of the cathedral and street cars? Would love to see a higher-resolution version!
Check out the Minnesota Reflections site, especially the photos contributed by the Minnesota Streetcar Musuem which has a large collection (only some of which are currently available from the site): https://reflections.mndigital.org/?f%5Bcollection_name_ssi%5D%5B%5D=Minnesota+Streetcar+Museum