The Pennsylvania Railroad had a siding at Mt Washington about 5 - 7 miles north of Baltimore station on the Northern Central to Harrisburg. It was used for loading / unloading horses bound for Pimlico race track which is the home of the Preakness.
The siding was about a mile or two from the race track and horses used to be shipped in / out via the PRR for Pimlico. My school bus went over a bridge that spanned the tracks, and on a few occasions I saw a B6 0-6-0 switcher sitting at Mt Washington with a horse car. This was somewhere around 1949-'52.
