Walnut Grove is an archaic placename in Yavapai County, Arizona, United States. It has an estimated elevation of 3,668 feet above sea level. When Prescott was selected as capital of the Arizona Territory in 1864, an amendment to select Walnut Grove as the capital instead failed on a 9-8 vote, as did votes to locate the capital at La Paz or a new proposed t…Walnut Grove is an archaic placename in Yavapai County, Arizona, United States. It has an estimated elevation of 3,668 feet above sea level. When Prescott was selected as capital of the Arizona Territory in 1864, an amendment to select Walnut Grove as the capital instead failed on a 9-8 vote, as did votes to locate the capital at La Paz or a new proposed town to be called Aztlan.