Yet, the natural beauty of Arizona always remains. Arizona’s saguaro cacti stand as guards over the beautiful Sonoran Desert. Arizona’s ponderosa pine forest is the jewel of Arizona’s rim country. The natural rock formations of the land in northern Arizona are a photographer’s dream. Arizona, a land of contrasts and of natural wonders! What are some of the challenges facing Arizona today? One challenge is pollution of the air. Some scientists think that dirty air could be causing changes in the weather all over the world. Some sources of air pollution in Arizona are exhaust fumes from cars and planes, smelters, and blowing dust. Another challenge is energy. Energy provides the power that makes things work, like lights and television sets. We need to develop more sources for energy. Palo Verde nuclear power plant creates electrical energy for Arizona, Texas, New Mexico, and California. Alternative fuel cars are replacing cars that run only on gasoline. New hybrid cars now run on both gasoline and electricity. Since the sun is a natural source for energy, Arizonans are trying to find other ways to use its power. Arizona has more than 300 sunny days each year. Some homes and office buildings now have solar panels on their roofs. The panels absorb the sun’s energy and change it into electrical energy. This solar electricity can then be used to run our homes and offices. Another source for energy is the heat from under the earth’s surface. This collected heat is called geothermal (earth-heat) power. In 2004, seven sites in Arizona were using geothermal energy. These direct use sites were located in Marana, Safford, Castle Hot Springs, and the Hyder Valley. Arizona is the second fastest-growing state in the country. Many people move here every year. More people create a need for more jobs and more homes. City streets and highways are often overcrowded. By 2030 the population of Arizona is expected to double. More water will be needed for this Modern freeways help the citizens of Arizona’s largest cities travel from their homes. But as Arizona’s population continues to grow, new methods of moving people may have to be developed. Chapter 1 • Arizona Today  9