Long before we built railroads, interstate highways and airline systems, the country’s circulatory system was its vast network of rivers, which spread across our landmass like life-giving veins and arteries. Even today, people gravitate and have a preference for living near or alongside waterbodies, whether coastal, lakeside or riverfront. Major cities in the United States, as well as in countries around the world, have tended to develop along rivers, giving them access to navigation, the exchange of goods, agricultural irrigation and sources of power.