SOQUEL, Calif. — Across the country, Democrats are winning primaries by promoting policies like universal health insurance and guaranteed income — ideas once laughed off as things that work only on the “Left Coast.”

At the same time, national politicians from both sides are finally putting front and center issues that California has been grappling with for years: immigration, clean energy, police reform, suburban sprawl. And the state is home to a crop of politicians to watch, from Kevin McCarthy on the right to Gavin Newsom and Kamala Harris on the left, part of a wave that is likely to dominate American politics for the next generation.

California, which holds its primaries on Tuesday, has long set the national agenda on the economy, culture and technology. So maybe it was just a matter of time before it got back to driving the political agenda, as it did when Ronald Reagan launched his political career in the 1960s. But other things are happening as well. The state is a hub for immigrants, a testing site for solutions to environmental crises and a front line in America’s competition with China. On all sorts of big issues that matter now and will in the future, California is already in the game.

In a way, California even gave us Donald Trump. So much of his “training” to be president came while he was an entertainment celebrity, on a show that, for a stretch of its existence, was produced in Los Angeles. And of course the means of his ascent — the smartphone, social media — came out of Silicon Valley. That’s a lot to have on a state’s conscience.