Railroad car ferries were fairly common in Louisiana many years ago. And one of those ferries was a part of the Southern Pacific. I came across the image below sometime back and it was a ferry that I’d never seen before. I decided to learn a bit more about it and digging around on the internet, I found pieces and parts which I’ve tried stitching together here.
The first thing I noticed when studying the photograph was the large “Southern” on its side. I didn’t recall the Southern Railway as having car ferries in the New Orleans area, so wondered if the word “Pacific” was hidden behind the curvature of the hull. The second clue were the initials “ML&TRR”. That turned out to be Morgan’s Louisiana and Texas Railroad or more fully, Morgan’s Louisiana and Texas Railroad and Steamship Company. Wow! Reading a bit more on Wikipedia, the ML&TRR had become an operating subsidiary of the SP. The SP at one time had quite the maritime empire, including both ships and ferryboat operations. In the New Orleans area they had railroad car ferries operating between Avondale and Harahan, and Algiers and New Orleans. This photograph appears to be the latter location, with the docks in New Orleans on the east bank of the Mississippi. There is much more information at these Wikipedia links if you’d care to learn more about these operations: History of the S.P. and T&NO Railroad.

The freight cars shown are interesting, the Orient car is the Kansas City, Mexico and Orient Railway (KCM&O). The other car appears to be the Chicago, Milwaukee, St. Paul & Pacific (CMSP&P), better known as “The Milwaukee Road”. Both appear to be all wooden cars utilizing truss rod construction, and supported on arch bar type trucks.
After doing all the research, I found this same photograph on Shorpy (which has a huge library of images dating back into the 1800s). Some of the information that I had already discovered was on their description of the photo, and in the comments therein, and they date the time as circa 1910. Unfortunately, even Shorpy doesn’t identify the photographer.