United States (History), history of how the republic developed from colonial beginnings in the 16th century, when the first European explorers arrived, to modern times. As the nation grew, it expanded westward from small settlements along the Atlantic coast, eventually including all the territory between the Atlantic and Pacific oceans in the middle of the northern continent -American, as well as two non-contiguous states and a number of territories. At the same time, the population and economy of the United States have grown and changed dramatically. The population became more diverse as immigrants arrived from every country in the world. From its beginnings as an isolated English colony, the United States has developed the world's largest economy. Throughout its history, the United States has faced struggles, both domestically—among various ethnic, religious, political, and economic groups—and with other nations. Efforts to address and resolve these struggles have shaped the United States of America into the 21st century. This is one of seven major articles that together provide a comprehensive discussion of the United States of America. For more information about the United States, please see the other six major articles: United States (Overview), United States (Geography), United States (People), United States (Culture), United States (Economy) and United States (Government).II Early Cultural InteractionPrinted Preview of SectionEarly American history began with the collision of European, West African, and Native American peoples in North America. Europeans “discovered” America by accident, then created empires from the conquest of indigenous peoples and the enslavement of Africans. Yet conquest and slavery were accompanied by centuries of cultural interaction – interaction that was a disaster for Africans and Native Americans and a triumph for Europeans, of course, but an interaction that transformed all three peoples in the process. A Native America in 1580The lands and human societies that European explorers called the New World were in fact very ancient. During ice ages, much of the planet's water was bound by glaciers. Sea levels have dropped several hundred meters, creating a land bridge between Alaska and Siberia. Asians crossed the border to become the first human inhabitants of the Americas.