Boundary Cone, Volcanic summit in Black Mountains, Arizona, United States

Boundary Cone is a cone-shaped rock promontory in the western foothills of the Black Mountains, in Mohave County, Arizona. It stands east of the Mohave Valley, about 4 miles (6 km) southwest of Oatman and 12 miles (19 km) east of the Colorado River, near Needles, California.

Boundary Cone was a landmark for early travellers crossing the Mohave Valley, and in March 2006 the Bureau of Land Management found it eligible for the National Register of Historic Places, with the Arizona State Historic Preservation Office concurring, for its traditional, religious and cultural importance to several Indigenous tribes.

Several Indigenous peoples attach religious and cultural importance to Boundary Cone and the surrounding landscape. In March 2006 the Bureau of Land Management determined, with the Arizona State Historic Preservation Office concurring, that the peak is eligible for the National Register of Historic Places as a property of traditional, religious and cultural importance to several tribes. It was not listed.

The best time to visit is during cooler months from October to April, as summer desert heat can be extreme. Bring plenty of water and sun protection, and check trail conditions before heading out.

The name marks the geographical boundary between two distinct ecosystems, with Mojave Valley desert on one side and elevated mountain terrain on the other. This border position makes it a natural landmark in the regional landscape.