While traveling from the US to Canada or Mexico can be complicated logistically, there is no fee for doing so. It's different coming the other way, however, and in addition to the normal complexities with touring, there are also legal complications to take into account.
In this latest post from MusicThinkTank, Robert Lanterman offers several helpful tips for those crossing the border to perform in the US on how they can avoid devastating legal complexities they might otherwise risk.
"Before you leave and you can still use the internet without being charged egregious amounts, look up the customs information for the United States and while you’re here make sure you have your passport with you wherever you go.
Travelling across borders with your own instruments is a pain but it can be done. There have been horror stories of course, as with travelling anywhere. Customs destroying instruments, expecting drugs and breaking equipment to see if you’re hiding them there — the kind of incidents you see on television shows."