The United States, the third most populous country globally, accounts for about 4.6% of the worlds population. Within the next few years, the U.S. population, currently estimated at 299 million persons, is expected to reach twice its 1950 level of 152 million. More than just being double in size, the population has become qualitatively different from what it was. As noted by the Population Reference Bureau, "The U.S. is getting bigger, older, and more diverse." The objective of this book is to highlight some of the demographic changes that have already occurred and to illustrate how these and future trends will reshape the nation in decades to come.