Pretty much anything that combines mapping, cultural perception, and geography is catnip to me, so I had to check out the results.
Just for kicks, let's start with the actual Census Bureau definition of the Midwest.
Seems reasonable enough. You could throw in Oklahoma, or debate whether the Dakotas, Nebraska, and Kansas are the Plains states and thus specifically not the Midwest. But seems about right.
People who indicate that they've spent "all" of their lives in the Midwest (374 responses) give a similar response, which includes Oklahoma, and a bit of Arkansas and Kentucky.
A lot of people consider Oklahoma Midwestern, as well non-Appalachian Kentucky. The Appalachians, the Rockies, the Confederacy, and Texas pretty much mark the boundaries. Among Midwesterners, there's common agreement on the Census definition.
Now, the definition of the Midwest gets much more expansive among the 723 people who have never lived in the so-called Midwest. For them, this region includes anything that's not desert, mountains, a coastal state, or the Deep South.
Idaho? No. Memphis? I wish.