Final answer:
Grain and lumber mills in New England during colonial days were primarily powered by water, utilizing water wheels and turbines connected to the machinery. This method of power was also used in textile mills in the region.
Step-by-step explanation:
Grain and lumber mills in New England during colonial days were powered mainly by water. Water-powered mills utilized the power of rivers to spin water wheels and turbines, which in turn powered the machinery involved in grinding grain and sawing lumber. This method of power was widely used in textile mills as well in New England, where water sources were abundant and provided a reliable source of energy.