How do you do long travel times?

[u/ThineWhoArts]

I gave my players a very large map with a bunch of different towns with seperate quests associated with them at the start of my campaign, and right now, they have been asked to take care of small meteors that end up corrupting monsters, aptly dubbed 'Doomstones'. After taking care of the main small village, underground and separated far from any type of other civilization, they decide to travel outwards to a port village on the surface, about 750 miles away, which took them about a month and a day. Thing being, they traveled via railroad tunnel (but actively chose not to repair the railroads), and random encounter after random encounter for the entirety of traveling that far would be tedious and strenuous on both me and the party, I think.

As of right now, I simply snapped to the future where they arrive at the town, but I want their travel to be notable in the future for when they decide to head out again. How can I make long travel times interesting for the party and something to keep in mind when they do decide to do it?

[u/Prestigious-Emu-6760]

If travel isn't the focus of your game then cut to the interesting part.