What are the problems of mapping landmasses in the 18th century?

Every map is an imperfect picture, in that way. Take Florida. Florida was hard to map in the same way that Lake Michigan was hard to map because it runs so north-south and is so relatively narrow in an era where you can't accurately measure longitude. It was really hard to tell where you were east-west and, with Florida, if you're a few miles off, the lines don't make any sense. Map-makers just threw up their hands. There are maps in which Florida appears as a series of islands. Sometimes, it's just this little narrow triangle. They know it's a peninsula, they don't know what shape it is.

Then Britain takes Florida at the end of the Seven Years War in 1763. They win the war against France and Spain and, as part of that, they get Florida, which had been Spanish for 200 years. But Britain doesn't actually know what Florida looks like because none of the maps agree. The print-makers of London want to put maps out to show what we have won, but they don't know what Florida looks like, so they're just guessing. The map-maker decided "I'm going to make Florida look like I think it should be because I have no way of knowing what it is."

What are you working on now?

It's the project related to George III. It is his vision of America when he first comes to the throne between 1760 and 1764. I'm looking at the vision he's bringing to the throne because he's only 22. He takes a much more active role in shaping policy than George II. George III comes in with an idea that Britain is too involved in the continent of Europe, is too tied to European affairs. He comes in with this idea of separating, withdrawing from Europe. Very much Britain first. He favors healing the divisions between Scotland and England and unifying the British Isle first. But he comes to the throne in 1760 during the Seven Years War, and when it ends, all of the treaty terms are happening in America.

He and his chief advisor, the Earl of Bute, realized they had to figure out how America fits into this idea for a unified Britain that they'd been cooking up. That's where they start coming up with grand schemes like drawing big boundary lines down the Appalachian Mountains. Florida looks like a good idea, from this perspective, because it might not be worth anything, but it makes America complete. It makes it whole, it makes it unified. There are no longer Spanish enclaves, combined with taking Canada from the French, which also happens at the end of that war. So, we can do in America what we want to do in Britain. How we reform America and how we want to reform Britain those things will work together.