Its not so much the actual passpt (though of course for 99% this will be the same as country/residence) but where you live-and must have official proof of that to show if asked (as such rare).

EUrail is since a few yrs same price and conditions as InterRail-but InterRail=meant for EUropeans (includ. even the BRits!) allows only 2 days to travel in own country/residence. As many expats want to use it to visit family etc. this may be a determining factor.

In your case you can choose-and just show whatever passpt is chosen-it seems to me that for this trip its as such wiser to take both-entry into EU/Schengen area is much easier if you have passpt from there.

BTW-does Denmark even allow dual citizenship? Or did you simply only mean the ´green card´?

Denmark does allow dual citizenship as of recently, but sorry to clarify, you’re recommending interrail? It is about 50 dollars cheaper so I would prefer it :)

If you are a US residents you should buy a Eurail pass and bring your US passport. However, no one will question if you buy an Interrail pass and use your Danish passport.

But with an Interrail pass having Denmark as country of residence you can only travel in Denmark on 2 travel days, the outbound/inbound rule.

So, it really depends on where you plan to travel. If you plan to travel for more than 2 days in Denmark you should buy a Eurail pass unless you want to pay separately for those travels in Denmark.

@Anna Viola Westberg