STS040-614-39 Huntsville, Alabama This near-vertical photograph of north-central Alabama highlights the westward-flowing Tennessee River and reveals diverse land use. Two sizable urban areas are visible--Huntsville, (north of the river, with an estimated population of 150 000) and Decatur (south of the river, with an estimated population of 40 000). U.S. Highway 72 Alternate is the main artery connecting these two northern cities, which are 20 miles (30 kilometers) apart. The parallel runways of the commercial airport serving both cities can be seen just south of U.S. Highway 72 Alternate, almost midway between Huntsville and Decatur. In addition to the manmade infrastructure of Huntsville (highways, commercial patterns), NASA George C. Marshall Space Flight Center and the U.S. Army Redstone Arsenal are discernible southwest of downtown Huntsville, near the Tennessee River. North-south-oriented Interstate Highway 65 crosses the landscape just east of Decatur. Agricultural production throughout the region includes a variety of crops (cotton, soybeans, and corn) and farm animals (poultry, hogs, and cattle).