The term 'Neighbor of Arizona' can be answered by two crossword solutions: Utah (4 letters) and Sonora (6 letters). Utah is a state located in the western United States, bordered by Idaho to the north, Wyoming to the northeast, Colorado to the east, Arizona to the south, and Nevada to the west. Sonora is a state in northwestern Mexico, bordered by the states of Chihuahua to the east, Baja California to the northwest, and Sinaloa to the south. Both Utah and Sonora are neighbors of Arizona.