This is the year that Baby Boomers and Millennials reach parity in their respective shares of the American population (75 million each).
The 2016 election will see the massive Baby Boom Generation eclipsed in size by voters under 35 years old. Since 1968, when the oldest Baby Boomers became of voting age (26th Amendment lowered voter age from 21 to 18 in 1971), they have had a profound impact on the politics of the country, finally reaching the White House with Bill Clinton in 1992 for the Democrats and George W. Bush in 2000 for the Republicans. Barack Obama is a youngish member.
Millennials self-report and register more as independent, but they are more liberal, and at least in 2008 and 2012, voted much more Democratic.
Pew Research: This year, Millennials will overtake Baby Boomers
Gallup: U.S. Baby Boomers more likely to identify as conservative