The miners in these areas felt isolated from the Washington Territorial government in Olympia, well to the west. When this was combined with the desire of the citizens in the Puget Sound area not to end up being outvoted by all the voting-age miners flooding in to the eastern parts of the territory, it was a popular decision all around to create a new territory of Idaho.
Thus in 1863, Washington Territory was trimmed in size to a width that essentially matched that of Oregon to the south, and the eastern part of Washington became Idaho Territory. This new territory, though, was created much larger than just that, for Idaho took in also the western half of the Dakota Territory and five degrees off the western part of Nebraska, Idaho’s eastern border being set at the 104th meridian. This not only incorporated into Idaho the gold mining region around Bannack and Virginia City, but it also cut Dakota down to about seven degrees in width, which was becoming something of a standard size for territories as they moved towards statehood. For good measure, the northeast corner of Utah was cut off and given to Idaho, the federal government once again demonstrating its bias against the Mormon government of that territory.
This new territory of Idaho was really too large to be sustained, especially as the eastern mining towns, such as Bannack and Virginia City, were separated by the rugged Rocky Mountains from the western mining towns and the capital city of Lewiston. Almost as soon as the Idaho territory was created, the settlers to the east of the Bitterroot range began to ask for a new territory and for a seat of government more accessible to them.
A champion for their cause appeared in Sidney Edgerton, who had been appointed by Abraham Lincoln as first Chief Justice for Idaho. Edgerton and his family set off for Idaho from Washington in 1863, but they ended up stranded in Bannack, unable to make it across the mountains to Lewiston. Edgerton soon realized the wealth of the eastern mining camps and he was converted by the miners there of the cause of splitting off a new territory from Idaho.
The eastern border of Montana extended to the Dakota Territory and the southern border was set at the 45th degree parallel so that there was room ultimately for two states between Colorado and Canada. Idaho was thus reduced in size close to what had been the eastern part of the original Oregon Territory, but not quite.
The original Oregon Territory had extended to the continental divide in the east, however about half-way up Idaho’s new eastern side, the border stopped following the continental divide and instead turned west to follow the Bitterroot Mountains. An old story said that this was because the survey party had gotten so drunk that they didn’t realize they had taken this wrong turn, but the true story is even more interesting.
When Judge Edgerton had first arrived to take up his judgeship, the territorial governor, William Wallace, had appointed him to a remote district east of the Bitterroots in order to show his contempt for judges imported from the east. Wallace aggrieved the wrong man, for with Edgerton's political connections, he was able to change the border between Idaho and Montana to the advantage of the new territory—-of which Edgerton was appointed first territorial governor—-by adding the fertile Bitterroot Valley to Montana instead of Idaho.
The Civil War years saw many significant changes to the political borders of the American West, something which continued for the rest of the decade, as we'll see in the next blog in this series.