John D. Rockefeller's Standard Oil, local & long distance phone companies, and railroads were all monopolies at one time. Currently, the U.S. postal service is a monopoly, because it is the only company that can legally offer it's services. Also, the local water and electric companies have a monopoly on your home, because if you are going to use either water or electricity, you can not buy it from another company, and use their electrical wires or pipes.