Mile 143.4 - Here's what Thomas Hahn has to say (from Towpath Guide):
Pass under WMd R.R. trestle (rebuilt 1917), now abandoned. R.R. crosses to continue upstream on opposite side of river. This is first of three crossings of WMd. right-of-way across canal in this section. WMd. R.R. crosses Potomac five times due to meanderings of river. R.R. was constructed 1904-1906 as part of Gould interests to obtain throughline from interior to coast. Syndicate was owned by W. Va. Central R.R. with eastern terminus at Cumberland. It bought control of WMd. R.R. from City of Baltimore, western terminus then at Big Pool, Md., W. of Williamsport. Linking these two points involved crossing the canal at various points, a privilege not readily obtained from receivers of canal controlled by B & O RR. With help of Md. legislature, rights were obtained, and payments for abutments, such as one at this point, helped B & O recoup a little of its losses--the very losses it was incurring to keep the canal operating so that its rival, the WMd. R.R., might not acquire the route in a forced sale! Back along R.R. track it is 3/4 mi. to Little Orleans. The WMd. R.R. is now abandoned between Hancock and North Branch; track removed.
Now you know why I love this guy. This trestle doesn't look like much but it has a story to tell.