I want her to have to travel THROUGH a lot of different states on the way - is this possible? (This sounds totally absurd and implausible, but for story reasons, I need her to stop off in different states.)
People from Britain trying to comprehend North American distances are
adorable*.
This is so possible it’s more possible than possible.
To get to the deep south from anywhere in the USA
other than the deep south requires driving through more than one state.
Eastern states are smaller than Western states ** so if you want to drive through lots of states your character could start in Portland, Maine and end up in Florida. From Maine, you’d be driving through ME, NH, MA, RI, CT, NY, NJ, DE/MD (depending on which way you go and if you want to spend $10 crossing the Chesapeake Bay Bridge Tunnel), VA, NC, SC, GA*** to Florida. That’s 13 or 14 states. That’s at least two days of solid driving but you could do it in a week, easy peasy, by stopping to look at cool things (Boston, New York, take the Cape May ferry to Delaware, Ocean City, Assateague Island, Colonial Williamsburg, Jamestown Settlement, Barrier Islands, Atlanta, etc.) There are a bunch of National Parks on that route, depending how you go. Or you could swing slightly West, avoid the Chesapeake Bay Bridge Tunnel, and go to Washington, DC.
I’ve driven all over this part of the country and lived in Virginia, New Jersey, Maryland and Connecticut. Actually, I’ve driven through almost every state in the Union (Louisiana, Alabama, North Dakota and Alaska excepted) and most of the Canadian provinces, also. Feel free to PM.
Ending up in Louisiana is a different route with even more states. Find a good map with all the highways (motorways) and state routes (sort of equivalent to A roads).
Be aware that travel times between distances in the US and Canada are
very different than parts of the UK. I budgeted an hour to go 55 miles in Scotland. That was nowhere near enough time.
* Friends from Kent were visiting San Diego, California when I lived in Sacramento, California and asked if I wanted to have dinner with them. They were quite taken aback when I told them sure, I could no doubt take Friday off work, have dinner or any other meal on Saturday and drive home Sunday. We were in the same state! It had to be close! It’s at least an 8 hour drive, really. Almost two Britains could fit in California.
** I do remember my delight the first time we drove from Virginia to New Jersey. I grew up on the West Coast. It takes all day just to get out of your own state. In less than four hours we’d driven through VA, MD, DE and half of NJ.
*** For translations of these two-letter codes, look up US Postal Service state abbreviations. All states have a two-letter code. FL=Florida, for example. Don’t get confused by all the different ones for states that start with A or M. MA is not Maryland, frex, it’s Massachusetts. MD is Maryland.