This issue's cover image depicts a section of the international lower Colorado River. Along this 38 km (24 mile) stretch, the river forms the international boundary between the states of Arizona and Baja California. Apart from this short stretch, the Colorado is a transnational river, originating in the United States and flowing into Mexico.

The Colorado once flowed with enough volume to allow steamship passage far upstream into the United States; at one time, it was navigable during high water as far as the Virgin River in Nevada, some 500 miles from the Gulf of California. It was demand for fuel by these steamships that decimated the lower Colorado's riparian woodlands, now taken over by such non-native species as the Tamarix seen here. Today, because of impoundments and abstractions, this stretch of the Colorado can normally float only kayaks and canoes.

The cover photograph is copyright Len Milich.