Only peripherally related to the point at hand:

"Historically, 100th meridian west:

In the United States, this meridian roughly marks the boundary between the semi-arid climate in the west and the humid continental and humid subtropical climates in the east" (IIRC this has to do with the western boundary of northward-migrating moist air asses from the Gulf Coast)

Personal anecdote:

Only in the last year or so occurred to me that on my maternal side:
- ancestors of both maternal GF and maternal GM emigrated from England to the Boston area in the 1650s and commenced farming
- they farmed their way steadily westward generation by generation (Connecticut, Pennsylvania, Ohio, Iowa...), ultimately arriving at literally 99 degrees west longitude just in time for the 1930s Dust Bowl
- a cumulative 28 degrees west longitude (71 to 99 degrees) in 280 years, or around 25 miles every ten years ~= 50 miles/generation
- until around 1930 when the younger generation said, stuff this and headed (via Model A) 22 more degrees west to the California and Washington to become small merchants

-- sutton
wouldn't have minded inheriting a dozen acres or so outside of Boston