While, before either Nevada and Arizona became a State, the border was switch from straight line north of Las Vegas to the Colorado river, which in effect moved Las Vegas from Arizona to Nevada. Thus we could "move" the Grand Canyon into another state EXCEPT we will need the approval of Arizona. The reason for that is the US Constitution clearly states that the borders of a State can NOT be changed without that State's permission. Thus we can move the Grand Canyon but Arizona will have to agrees.
Article Iv, Section 3 of the US Constitution:
Section 3 - New States
New States may be admitted by the Congress into this Union; but no new States shall be formed or erected within the Jurisdiction of any other State; nor any State be formed by the Junction of two or more States, or parts of States, without the Consent of the Legislatures of the States concerned as well as of the Congress.Map of 1866 showing Las Vegas in Arizona:
http://www.geographicus.com/P/AntiqueMap/Southwest-johnson-1866Arizona Territory was stripped of Las Vegas in 1867 and given to the State of Nevada (a state as of 1864, so what is Now Southern Nevada was added to the STATE of Nevada after Nevada had became a state, but while Arizona was just a territory.
http://en.wikipedia.org/wiki/Nevada_TerritoryMap of the US showing Arizona including modern Southern Nevada in 1862:
Map showing the 1867 movement of Arizonao West of the Colorado to Nevada:
http://en.wikipedia.org/wiki/File:United_States_1867-01-1867-03.pnghttp://en.wikipedia.org/wiki/Territorial_evolution_of_the_United_States