Flatlander is a term used, disparagingly, by people living at higher altitudes—typically in smaller towns—to refer to those living at lower altitudes.

Flatlander in the United States refers to anyone not from a mountainous environment, a label applied by locals of a mountain region, either pejoratively or in well-meaning contempt, to outsiders.

In Vermont and Northern New Hampshire, a flatlander is any non-native, but particularly one from southern New England, Massachusetts, downstate New York, or New Jersey, and very particularly one who has recently moved to Vermont or Northern New Hampshire and would prefer that the state change to better accommodate newcomers, rather than the other way around.