Source: Pew Research Center

Every year, we look back at our research to select the most memorable facts that illustrate important trends shaping our world. At Pew Research Center, the topics we analyze range from the specific subjects of video gaming and family caregivers to broader areas like political attitudes, global climate change and religious affiliation.

It’s a hard task to select just 15, but here are some of our most striking findings of 2015:

1.  Just 19% of Americans say they can trust the federal government always or most of the time. That’s among the lowest levels in over 50 years. The long-term erosion of public trust is mirrored by a steep decline in the belief that the government is run for the benefit of all Americans.

2.  The American middle class is shrinking. After more than four decades of serving as the nation’s economic majority, the U.S. middle class is now matched in size by those in the economic tiers above and below it. A separate analysis also finds that globally, the middle class is more promise than reality. (See where you fit in the U.S. and worldwidewith our interactive calculators.)

3.  For the first time since the 1940s, more immigrants from Mexico are leaving the U.S. than coming into the country. The shift is due to several reasons, including slow economic recovery after the Great Recession that may have made the U.S. less attractive, as well as stricter enforcement of U.S. immigration laws, particularly at the border.

4.  There’s a substantial rise in the share of Americans who say the country needs to continue making changes to give blacks equal rights with whites. In July 2015, six-in-ten (59%) Americans said changes are needed, up from 46% in March 2014. These findings come in a year where racial tensions were high in much of the country, from protests over police shootings to student strikes at universities. Our poll also shows that a racial divide in public opinion persists: Blacks are much more likely than whites to say changes are needed.

5.  Millennials surpassed Baby Boomers in sheer numbers to become the largest U.S. generation. There are an estimated 75.3 Millennials (ages 18 to 34) compared with 74.9 million Baby Boomers. This racially diverse, economically stressed and politically liberal group is also taking over American jobs: Millennial workers this year grew to outnumber Gen X workers, making them the largest share of the U.S. labor force.

6. For news about politics and government, social media may be for the Millennial generation what local TV is for the Baby Boomer generation. Six-in-ten (61%) online Millennials say they get political news on Facebook in a given week, a much larger percentage than any other source for news. That’s a stark contrast to internet-using Baby Boomers, for whom local TV tops the list. These trends also reflect a major shift taking place in the news world, as social networking sites increasingly become an integral part of Americans’ news experience.

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