Courtesy of the Federal Railroad Administration:
Found by David Kudrav.
You can zoom and search and do all the stuff you are used to being able to do with an online map. You can see main lines (color coded by railroad), mileposts, station names, Amtrak, and even individual markers for each railroad crossing.
It mostly doesn’t bother to show sidings, branch lines, etc.
The station names are a bit.. off. Just in my area, almost all of them are at slightly different mileposts than the railroads’ timetables have, and some of the ones on the map appear to have been derived from a source other than the current timetable. I’m guessing the database they are pulling these from is not particularly up to date, and the railroads have moved them around and renamed them? Either that or they’ve just got bad data.We have found both situations where a line is shown without its mileposts, and also situations where the mileposts appear without the actual line they are on. (Mobile, AL has a notable case of the latter)But still, it’s the only free online thing I’ve seen that shows railroad mileposts on a reasonably accurate map.