A JOURNEY NORTH

In which Thomas Jefferson and James Madison go out on the trail of a crop pest—and much more.

Over a period of less than a month in the late spring of 1791, Thomas Jefferson and his fellow Virginian James Madison ventured far north up the Hudson River Valley with a pressing aim in mind. A pest called the Hessian fly was endangering New York wheat crops, for one, and Jefferson, both scientist and farmer, feared that the noxious critter would head south to Virginia and devastate farm yields there. The fly turned out not to be “Hessian” (that is, from Germany): It was homegrown, but “Hessian” was a term of opprobrium in that day. In all events, writes Rutgers historian Masur, Jefferson’s “study of the Hessian fly allowed temporary escape from partisan politics at a volatile moment.” That volatile moment drew suspicion around the Virginians’ journey: Domestic political opponents feared that Jefferson was trying to recruit northerners to the anti-Federalist cause, while a British consul feared that their mission was “to proselyte as far as they are able to a commercial war with Great Britain.” Hessian fly studied but undefeated, as Jefferson would note during his presidency, the two went on to observe what must have seemed a rare sight: a free Black farmer who worked a handsome, fertile spread with the aid of six white employees. Madison praised him for “industry and good management,” Masur notes, but it did not sway Madison to set his own slaves free. Other projects along the sojourn spoke to the Virginians’ encyclopedic minds: studying the potential of sugar maples to supplant cane sugar imported from the British West Indies, collecting Native American words, and so forth. The trip lasted only a few weeks, but, as Masur notes, it was memorable enough that the two friends spoke of it many years afterward.

A fluently written account of a small but meaningful moment in American history.