WHEN DAVID AND LUCY MARVIN started Butternut Mountain Farm in the mid-1970s, they wanted to try the road less taken. So David, a trained forester, turned to maple sugaring. “It was pretty unusual at the time,” says his daughter, Emma. 

The season in Johnson, Vt., for harvesting sap only lasts a brief six weeks every spring. But that narrow margin for error belies a long-term nature of the investment: Red maple and sugar maple trees have to be about 40 years old before their sap can be harvested for the first time. They can then continue to be tapped for the rest of their lives, sometimes a couple of centuries. 

Butternut Mountain is now one of the largest producers and distributors of syrup in the country, with 17,000 taps spread over 1,200 acres, a 75,000-square-foot processing and distribution facility, and 90 full-time employees. 

Today, business for the Marvins and their fellow American syrup producers is poised to boom, thanks not just to the technological revolution in the age-old art of sugaring but because of a free trade deal on the other side of the world.