1607 is notably known for the year where about 100 English settlers crossed the Atlantic to the New World and Founded Jamestown, the first colony in America. This is also the start of the massive groups of Europeans, mostly the English started colonizing the New World and creating multiple towns, then cities, then states.
The reason this Era of English Settlement ends is not because the English stopped arriving for England, rather, that the year afterwards (1734) would be the start of a massive religious movement; the Great Awakening. This movement would greatly change the shared views of religion and politics between the Church of England and the dozens if not hundreds of Protestant faiths that existed at the time.