Much public commentary in the early twenty-first century concerned the “millennials,” the new generation that had come of age in the new millennium. Commentators, demographers, and political prognosticators continue to ask what the new generation will bring. Pollsters have found certain features that distinguish the millennials from older Americans. They are, the pollsters say, more diverse, more liberal, less religious, and wracked by economic insecurity.

Millennial attitudes toward homosexuality and gay marriage reflect one of the most dramatic changes in popular attitudes toward recent years. After decades of advocacy, attitudes over the past two decades have shifted rapidly. Gay characters–and characters with depth and complexity–can be found across the cultural landscape and, while national politicians have refused to advocate for it, a majority of Americans now favor the legalization of gay marriage.

Even as anti-immigrant initiatives like California’s Proposition 187 (1994) and Arizona’s SB1070 (2010) reflected the anxieties of many, younger Americans proved far more comfortable with immigration and diversity–which makes sense, given that they are the most diverse American generation in living memory. Since Lyndon Johnson’s Great Society liberalized immigration laws, the demographics of the United States have been transformed. In 2012, nearly one-quarter of all Americans were immigrants or the sons and daughters of immigrants. Half came from Latin America. The ongoing “Hispanicization” of the United States and the ever shrinking proportion of non-Hispanic whites have been the most talked about trends among demographic observers. By 2013, 17% of the nation was Hispanic. In 2014, Latinos surpassed non-Latino whites to became the largest ethnic group in California. In Texas, the image of a white cowboy hardly captures the demographics of a “minority-majority” state in which Hispanic Texans will soon become the largest ethnic group. For the nearly 1.5 million people of Texas’s Rio Grande Valley, for instance, where a majority of residents speak Spanish at home, a full three-fourths of the population is bilingual. Political commentators often wonder what political transformations these populations will bring about when they come of age and begin voting in larger numbers.

Younger Americans are also more concerned about the environment and climate change, and yet, on that front, little has changed. In the 1970s and 1980s, experts substantiated the theory of anthropogenic (human-caused) global warming. Eventually, the most influential of these panels, the UN’s Intergovernmental Panel on Climate Change (IPCC) concluded in 1995 that there was a “discernable human influence on global climate.” This conclusion, though stated conservatively, was by that point essentially a scientific consensus. By 2007, the IPCC considered the evidence “unequivocal” and warned that “unmitigated climate change would, in the long term, be likely to exceed the capacity of natural, managed and human systems to adapt.”

Climate change became a permanent and major topic of public discussion and policy in the twenty-first century. Fueled by popular coverage, most notably, perhaps, the documentary An Inconvenient Truth, based on Al Gore’s book and presentations of the same name, climate change entered much of the American left. And yet American public opinion and political action still lagged far behind the scientific consensus on the dangers of global warming. Conservative politicians, conservative, think tanks, and energy companies waged war against to sow questions in the minds of Americans, who remain divided on the question, and so many others.

Much of the resistance to addressing climate change is economic. As Americans look over their shoulder at China, many refuse to sacrifice immediate economic growth for long-term environmental security. Twenty-first century relations with China are characterized by contradictions and interdependence. After the collapse of the Soviet Union, China reinvigorated its efforts to modernize its country. By liberating and subsidizing much of its economy and drawing enormous foreign investments, China has posted enormous growth rates during the last several decades. Enormous cities rise by the day. In 2000 China had a gross domestic product around an eighth the size of the United States. Based on growth rates and trends, analysts suggest that China’s economy will bypass the United States’ soon. American concerns about China’s political system have persisted, but money sometimes speaks matters more to Americans. China has become one of the country’s leading trade partners. Cultural exchange has increased, and more and more Americans visit China each year, with many settling down to work and study. Conflict between the two societies is not inevitable, but managing bilateral relations will be one of the great challenges of the next decade. It is but one of several aspects of the world confronting Americans of the twenty-first century.