@Butch shared a really cool old train groove from the early 1900’s on the thread Harmonica - The People’s Instrument, and I thought I’d re-post I in a new thread specifically about the Train, because it’s SUCH AN IMPORTANT TOPIC for harmonica players. Here’s his post from that thread:
In the book, Harmonica, Harps and Heavy Breathers, one of the early harmonica players from early 1900’s, Palmer McAbee has a couple recordings, 1928 it appears and his train if definitely something worth listening to, Have no idea how some of these sounds are done . . . https://youtu.be/3UvOzsyty_E and one of his songs, Lost Boy Blues, is https://youtu.be/WpA4gRmAyRc quite different from what Blues are now. But then, this is almost 100 years ago also . . . Really enjoying my history lesson on early harmonica, that’s for sure !
As the discussion progressed, I mentioned that only a handful of people can still play harmonica like Palmer McAbee, and one of them is Joe Filisko. I asked Joe if he has any resources about playing The Train groove.
He said this resource has some good stuff on the train (and it’s only $1.00.)
But then he sent me a link to this page that he wrote which says this at the top:
*From my experience, it’s my strong belief that the best possible way to expedite ones playing progress is by smartly practicing the Train. Committing 5 minutes a day to this is the most direct path to building better rhythm, tone, blues breath control, dynamics, relaxation, and throat tremolo. It’s also the easiest thing to do because it can be played using ONLY chords.
That page 
is really cool and is free so I recommend following the link and giving it a read.
I also believe that The Train is important which is why I have several lessons devoted to it in my Beginner to Boss course, and I know it was something I got a lot of pleasure from early on, and still get a lot of pleasure from now. But the way he stated it is SO STRONG, it inspired me to start this thread devoted exclusively to the topic.
BTW, he also mentioned this 80 minute masterclass resource, which is $40, but as he said is “mega-complete.”
Joe is one of foremost living experts in harmonica - he is a master player, technician, and historian - so I’m sure the masterclass will not disappoint!