Race

According to recent estimates by the Centers for Disease Control and Prevention (CDC), there are more than one million HIV-positive people in the United States. Deaths associated with AIDS number more than 18,000 a year, while 56,300 new HIV cases are reported annually.

The United States is a country founded by immigrants, yet immigration has never failed to stir controversy. Much of the discussion centers on illegal immigration, but the number of people who arrive legally and their contributions to the U.S. economy — or their cost — has also elicited debate.

Since the beginning of the HIV/AIDS epidemic in the 1970s, millions have been infected and died. In 2010, more than 34 million worldwide were living with the disease, and despite significant resources dedicated to prevention, thousands more become infected every day. Prevalence varies significantly by country, from estimates of less than 0.1% in Bangladesh, Egypt and Japan to more than 23% in Botswana, Lesotho and Swaziland.

In the first half of the 20th century, a convergence of social attitudes, market forces and government policy in the United States contributed to significant increases in racial segregation. While segregation continues to be seen as a significant problem, a 2012 analysis of historical U.S. Census data indicates that racial separation has diminished significantly since the 1960s.

For millions of Americans, issues of racial and ethnic identification are frequently complicated, a legacy of the country’s endless waves of immigration as well as its long history of slavery and expansion into Native American lands across the continent.

How we communicate has changed rapidly over the last few years, and some of the greatest changes in behavior have been seen among teenagers, who are often “early adopters” of technologies. New applications and gadgets, though, can now quickly become commonplace and mainstream.

Big cities dominate America’s cultural consciousness in ways that the countryside — amber waves of grain notwithstanding — can only dream of: Manhattan skyscrapers, L.A. movie stars and Chicago’s “big shoulders,” as Carl Sandburg put it in his 1916 poem. Cities can have political power, too, embodied by recently departed but long-serving mayors such as Boston’s Thomas Menino (21 years), Chicago’s Richard M. Daley (22 years) and New York’s Michael Bloomberg (12 years).