Dear Scotsman;
A national fishing license has been wished for years, but isn't going to happen. I've fished in most states (and a few other countries),, and there are very few things in this life more frustrating than understanding the laws and few rewards greater than catching the variety of fish we have in the USA. For instance, some states don't consider "barbless" hooks to be previously barbed hooks where you bend down the barbs. I nearly got a fine for that in Maine. However, you can hardly purchase or find them.
Sometimes you don't need a license for salt water, and there are some days in some states that you don't need a license, like National Hunting and Fishing Day, this year September 22. Sometimes there are special licenses for federal waters, like Yellowstone. It is very difficult to summarize anything, but here is a great resource:
https://www.takemefishing.org/get-a-fishing-license/
Licenses can be bought in almost all states online. One, three and sometimes seven day licenses are very handy. Fish and Game officers will accept the license displayed on your smart phone or computer screen if they are in a good mood.
I haven't done the great loop, but you might study each state's laws carefully since rivers often are state borders. For instance, fishing the Columbia River parts that divides Washington and Oregon you can use either license so you wouldn't have to buy each if you only pass through there. Just don't bring the fish uneaten into Washington if you have the Oregon License.
I grew up on the Chesapeake bay, and if you pass through there in the summer or fall you definitely want to catch and eat blue crabs, a great Maryland experience. They are also along most of the east coast, but people there don't relish them like Marylanders.
Gathering shellfish, clams, oysters, etc., adds a lot to your fare. Most states post maps of contaminated sites, so avoid them.
I would love to hear how your fishing goes. I plan the exact same thing when I retire.
