Why Might the Old Northwest by the 1840s Be Better

Why might the Old Northwest by the 1840s be better referred to as the "Yankee" West?

A) At least 40 percent of the migrants to the Old Northwest came from New England.
B) Most farms in the Old Northwest were owned by absentee merchant landlords in Boston.
C) Dutch settlers from around Yonkers, New York, made up 50 percent of the migrants to the Old Northwest.
D) Most of the trade with the Old Northwest was through New England seaports.