The America of today bears little resemblance to the country of 50 years ago. It is older. It is less white. And those two demographic trends will only accelerate over the next 50 years.

“Each of these shifts would by itself be the defining demographic story of its era,” writes Paul Taylor of the Pew Research Center. “The fact that both are unfolding simultaneously has generated big generation gaps that will put stress on our politics, families, pocketbooks, entitlement programs and social cohesion.”

Taylor’s conclusions come in an essay titled “The Next America” that details the massive shifts roiling the country — and what they will mean for its politics going forward. (Taylor has also written a book by the same name.)

While neither of his broadest conclusions — the nation is getting older and less white — is groundbreaking, he explores the depth, rate and impact of these changes in a way that drives home a basic point: We are through the demographic looking glass.

Let’s start where Taylor starts — with the graying of our population. Medical advances and better eating habits are extending our lives to a point unimaginable even as recently as 1960. Back then, average life expectancy was a shade under 70; in 2011, it was nearly 79. (The gap between men and women has shrunk as well. In 1960, women lived on average seven years longer; in 2011 that advantage was less than five years.)

“We’ll have almost as many Americans over age 85 as under age 5” by 2060, Taylor writes, noting that what has always been an age pyramid — broad among the young and narrowing significantly as the age ranges rise — will turn into more of an age rectangle over the next five decades. (This phenomenon is not simply a result of people living longer; the birth rate is declining simultaneously.)

The aging of America is happening at the same time the gap between how young and old see the world, politically speaking, is wider than ever.

In the 2012 election, President Obama won voters age 18 to 29 by 60 percent to 37 percent, while losing those 65 and over by 12 points. That 35-point swing between youngest and oldest is all the more remarkable when you consider that as recently as the 2000 presidential election, there was virtually no gap in how those voters cast ballots. Al Gore won voters age 18 to 29, 48 percent to 46 percent, and voters age 60 and older by a remarkably similar margin: 51 percent to 47 percent.

The other major demographic shift is the declining white population and the surging Hispanic community.

As Taylor notes, the American population was 85 percent white in 1960, but by 2060, it is expected to be 43 percent white. By contrast, Hispanics, who were just 4 percent of the population in 1960, are projected to make up more than 30 percent by 2060, according to Taylor.

The political implications of these changes are profound and are already being visited on the two major parties. Mitt Romney won the white vote by 20 points in 2012 — the largest margin since Ronald Reagan in his landslide reelection in 1984 — but still lost the election convincingly. That’s because whites were just 72 percent of voters, the lowest percentage ever; it was the sixth-straight presidential race in which the white vote declined as a share of the overall electorate.

Combine the smaller white vote with Obama’s dominance among Hispanics (he won 71 percent of their votes) and African Americans (93 percent), and you see why he won easily among an electorate that simply looked different than it had in years past.

Perhaps the most interesting finding about ethnicity in Taylor’s piece, however, is not the projected growth of the Hispanic community or the shrinking of the white community, but rather the blurring of racial lines.

In 1960, just over 2 percent of the population married someone not of their own race. By 2010, that number had surged to 15.5 percent. As Taylor writes: “By 2050, will our racial categories still make much sense? These days our old labels are having trouble keeping up with our new weddings.”

The broad takeaway from Taylor’s outstanding work is that age and ethnicity are reshaping our country, and even our ways of describing each other, rapidly and meaningfully. Those changes mean that assumptions based on the past are extremely dangerous, in politics and everywhere else. We are entering a new age for America. Both parties need to acknowledge that reality and act — and react — accordingly.