One hundred years ago, 99 percent of us were farmers growing our own food, while 1 percent lived in the cities. Now those percentages have reversed—and yet we all have to eat. Where does our food come from? Despite shrinking farmland and the rise of big ag, every spring and summer the wheat belt in America’s heartland swells with amber waves of grain.

Many American farmers still turn to custom harvesters to cut their wheat. Each May, a dwindling number of these harvesters set out in convoys of equipment. Last season I followed one such crew, manned by Eric Wolgemuth, 57, and his exceptionally hardworking men and one woman, ages 20-25, from Lancaster County, PA. They are college students, farmers, and self-taught mechanical whizzes.