The Los Angeles metropolitan area includes five counties and covers 34 000 square miles (88 060 square kilometers). Nearly 10 million people live and work in this dynamic region. Los Angeles is important economically because of shipping, industrial facilities, distribution centers, and financial institutions. Several major interstate highways can be identified, and many of the large industrial and commercial areas can be identified by their highly reflective signatures. These clustered areas are usually found alongside major ground transportation routes. Downtown Los Angeles (near the center of photograph) can be seen west of Interstate Highway 5, which traverses southeast-northwest. Since this photograph is made on color infrared film, the reddish signatures represent vegetated areas; usually more intense red is indicative of vibrant vegetation. Not surprisingly, the red areas in this photograph (trees, grasses, and shrubs) are predominantly found on the mountains, hills, and parks that are scattered throughout the region. The two long, parallel runways of Los Angeles International Airport are visible southwest of the center of the photograph, midway between the Santa Monica Mountains to the north and the Palos Verdes Hills to the south. The color infrared film presents a crisper, sharper, and—in general—more detailed photograph than does the natural color film and allows one to identify additional physical features.)