Yuma County

  When a person gazes at a map of Yuma County, one thing becomes readily apparent, the lack of roads. Nearly all of the roads are concentrated in three areas, the Yuma Valley, which is in the southwest corner of the county below the confluence of the Colorado and Gila Rivers and also in the Mohawk Valley in the central part of the county. These two areas are separated by the Gila Mountains (also called the Fortuna Mountains). The third area is the Dome Valley, which wraps around the north end of the Gila Mountains and connects the other two areas.
  The Yuma Valley is by far the biggest of these areas and it lies along a wide floodplain that was created by the Colorado River. The river has wandered across this flat valley over the eons, carving new channels and abandoning old ones. The old channels are now plowed up and planted with a variety of crops. Looking at an  aerial map of this area will reveal faint swales in the farmland. These swales are ancient channels of the Colorado River.  The silt in this area, laid down by the river over thousands of years, is very deep and very fertile, creating one of the most productive farming areas in the United States.
  The Mohawk Valley is a long, linear area that lies mostly south of the Gila River, which is one of the principal tributaries of the Colorado. The Mohawk Valley is 25 miles long and seven miles at its widest point, but it averages only four miles in width. Interstate 8 and Old U.S. Highway 80, now a county maintained road, are the principal transportation arteries in this area. 
  The Mohawk Valley is also a productive farming area. The soil here was laid down by the Gila River. There are several towns in this area with the largest one being Wellton, which has about 2,000 people.
  The other area that contains most of the county's roads is the Dome Valley, which also lies along the Gila River. This area is narrower than the Mohawk Valley with an average width of only about two miles. There are no towns in this area, but there are quite a few farms.
  East of Mohawk Valley, are the Hyder and San Cristobal Valleys, that  have a much smaller road system and a much smaller population than the Mohawk Valley.  The major town in the San Cristobal Valley is Dateland, which grew up along U.S. Highway 80 and is now a major stop on Interstate 8, serving travelers on a remote stretch of highway. This area also lies along the Gila River. The only town in Hyder Valley is Hyder, which only has a handful of people.
  The only other populated place in Yuma County is Martinez Lake, in the northern part of the county on the Colorado River. I am undecided about whether Martinez Lake is a town or just a remote housing development, but I do know that there is a resort there. At any rate, about 300 people live here year round and several thousand more take up temporary residence during the balmy winter months.
  There are also some residential areas, and roads,  on the property of the Yuma Proving Ground, which is a military base that serves all branches of the military. The Proving Ground has about 3,700 people, from what I can gather.