The State of Lincoln has been proposed to consist of the Panhandle of Idaho and Eastern Washington (that is, east of the Cascade Mountains). It was first proposed by Idaho in 1865, when the capital was moved from Lewiston in December, 1864 to its present-day location of Boise in January, 1865, in an Idaho greatly reduced in land area. The original Idaho Territory, from a bill signed by President Lincoln in March, 1865, was declared by Governor William Wallace in Lewiston, July 4, 1863 and included present day Idaho, and virtually all of present-day Montana and Wyoming, making it larger in land area than Texas. Montana was made a territory in May, 1864 and the Panhandle was specifically excluded in order to prevent Lewiston, west of both the Continental Divide along the crest of the Rockies and of the Bitterroot Mountain Range, from remaining the capital. The reasoning was that Lewiston sits on the western edge, across the Snake River from Washington. Montana stretches to North Dakota. The 1865 proposal was to make the panhandle its own state. This proposal failed, but in 1901 another proposal was made, this time to combine the Idaho Panhandle with Eastern Washington to create the state of Lincoln, in honor of President Abraham Lincoln. A third proposal was popularized in the late 1920s to consist of eastern Washington, northern Idaho and western Montana to the Continental Divide. From the Washington end, proposals have been made as recently as 1996, 1999, and 2005. Idaho saw a corresponding campaign for North Idaho, financed by the sale of T-shirts reading, "North Idaho - A State of Mind". Other than Lincoln, the names "Columbia" and "Eastern (or East) Washington" were proposed to be used for the state.

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