Nick Patrick wondered if the colonists spoke with an English accent back in the Revolutionary days. He did some research and what he discovered was surprising:
I’d always assumed that Americans used to have accents akin to today’s British accents, and that American accents diverged after the Revolutionary War, while British accents remained more or less the same.So, there you have it. Now, along with trying to get them to spell color correctly, we're going to have to work on their pronunciation of aluminum.
Americans in 1776 did have British accents in that American accents and British accents hadn’t yet diverged. That’s not too surprising.
What’s surprising, though, is that those accents were much closer to today’s American accents than to today’s British accents. While both have changed over time, it’s actually British accents that have changed much more drastically since then.
For more details read his entire post: Did Americans in 1776 have British accents?