Complex sentence: In the spring of 1791, when Hemings and Jefferson were resident in Philadelphia, James accompanied Jefferson and James Madison on a month-long vacation, in which they traveled through New York and Vermont, stopping at Albany, Lake George, Lake Champlain and Bennington.
Split into simpler sentences: In the spring of 1791, when Hemings and Jefferson were resident in Philadelphia, James accompanied Jefferson and James Madison on a month-long vacation. The party traveled through New York and Vermont, stopping at Albany, Lake George, Lake Champlain and Bennington.