Writing about politics inspires a certain amount of déjà vu, time and again. Last week, like many before, served as a case in point.
President Obama unleashed a surprise shift Wednesday in the nation's relationship with Cuba, a loosening of the strictures that have bound the Cold War-era policy for upward of 50 years.
The news hit like a 7.0 on the San Andreas — due to both the sheer boggling fact of it and the ability of the administration to keep the endeavor that rare thing in Washington: a secret.
But a look at voter sentiment about Cuba and specifically the measures long imposed against Castro's island underscored what made Obama's entreaty possible: the fact that hard-line support of anti-Cuba measures has eased over the years, quite literally dying off.
It was a reminder that what drives politics more often than not is a steady, if lesser-noticed, creeping of the fault lines of public sentiment well before the big jolt hits. In California, prone to quakes of the physical and political, this comes as no surprise.
Obama's Cuba move rested on the fact that younger and in many cases non-Cuban voters, all of whom come at the issue from a completely different cultural perspective, are asserting their strength in Florida, the only state where the issue ever really commanded huge attention. Where once Cubans were the significant nonwhite voting bloc in the state, they are now one of many, their power diluted by the influx of other Latino groups and, further, by disagreements within their ranks.
The same sort of demographically driven acceptance of a position that would have been unthinkable a half-century ago has pushed the country toward acceptance of same-sex marriage. (And fast: Former San Francisco Mayor Gavin Newsom was treated like a pariah by many in his own Democratic Party when he sanctioned marriage licenses for gay couples just a decade ago.)
The fault lines have similarly crept toward legalization of marijuana, and in favor of easing the way those in the country without legal immigration papers are treated.
Ethnic and racial diversity is an inexorable shaper of what the country thinks, but so too is youth. And both are forces wholly out of the control of the political parties, which in many ways are simply along for the ride.
That can be seen in the course of any campaign or in public polling, whether it centers on 2014's Republican-leaning electorate or the Democratic one from the presidential contest two years before, or any before that.
On the issue of Cuba, a Florida International University poll asked Cuban Americans whether they favored or opposed continuation of the embargo against Castro. Among those 65 and older, who have an acute and in many cases personal memory of the wrenching conflicts of the past, 60% favored the embargo. Among those age 29 and younger, only 8% felt the same way. (Overall, 48% supported the embargo and 52% opposed it, a split that foretold the shrunken power of the issue.)
President Obama's unilateral moves this fall to expand groups of immigrants who will be protected from possible deportation also have found wide support. Among those 29 and younger, a national Pew Research poll found, 54% supported Obama's move, 15 points higher than the percentage of those 65 and older in support.
On same-sex marriage, the Gallup polling organization found that among those ages 18 to 29, 78% felt that same-sex marriage should be legal. Among those 65 and older, it was 42%.
Older Americans are, of course, more dependable voters than the young. But the young eventually age, and as they do their views take on even more power. Republicans and Democrats have launched efforts to corral younger voters not just because of the impact in the moment but to build relationships that will persist across the decades.
A telling look at what it means can be seen in California, a young and ethnically diversified state, and one whose stances have been driven leftward by sharp demographic changes.
The Field Poll has repeatedly charted how voter views on some social issues have shifted over the previous three decades.
In 1977, 28% of California voters backed same-sex marriage; by 2009, 49% did. By 2013 that had grown to 61%. In 1969, 10% favored legalization of marijuana under controlled conditions; by 2013 47% did.
And then there is immigration. Asked in 2006 whether longtime immigrants without proper documents should be able to apply for citizenship under certain conditions, 75% said yes. By 2013, it was nearly unanimous, at 90%.
Granted, the state may be far more influenced than others by youth and the influx of immigrants from Mexico and elsewhere, but even a minimized version of California's experience has the power to alter places beyond its borders.
The struggle for Democrats is to energize their younger and more diverse voter groups, which tend to need more nudging to show up than older and more reliable Republican voters. The struggle for Republicans, however, is even more profound: to watch the fault lines roar toward their party's aging base.