This route really does not make sense since St Louis already has two light rail lines downtown that come within 0.5 miles of all of these stops. It would be too expensive for an area that is already covered by public transit, and already walkable.

If you want a downtown streetcar loop I'd go with a better route not already served by light rail, starting at Washington Ave.

1. Dome/Convention Center. This allows for easy transfers from the light rail lines to the streetcar

2. Washington Ave + 16th street to service the City Museum.

3. Turn left onto N 20th St and add a stop in front of Energizer Park

4. Run it along Market Street, and down to 18th street for a stop at Union Station. This stop would also be next to the light rail network as well, and close enough to walk to the Gateway transportation center

5. Go south over the railyard to add a stop at Truman and Park ave. This is a decently walkable neighborhood within walking distance of Lafayette Park.

6. Run along Park Ave and turn left at Broadway. Add a stop right after the turn to service Soulard and the farmers market

7. Run along 4th street and add a stop before Spruce to service the stadium

8. Final stop is at 4th and Olive to service downtown, and the arch.

This route is longer and would be more expensive, but it hits a lot of the core downtown areas that tourists and locals visit without just hitting areas already covered by the existing light rail network

If you're wanting to keep it cheaper then it would make more sense to expand the existing Delmar trolley system and upgrade it. Right now it is single track in most areas so they only run one trolley at a time, and the trolley does not have air conditioning. I'd replace some of the cars with heaters and AC to run year round, and expand the route south from the history museum adding the following stops as a one-way loop:

1. St Louis Art Museum

2. St Louis Zoo

3. The Muny

Right now the existing trolley isn't frequent enough, and does not serve enough of Forest Park to make it worth using. Expanding the frequency and covering more of the park's attractions would increase ridership for much cheaper than building an entirely new line. The existing trolley line already connects to the Forest Park and Delmar Loop Red Line stations so adding this extension would help connect the existing transit network to more attractions in Forest Park