In this moment of wildly disruptive politics, it’s actually possible to see President Trump, California Gov. Jerry Brown, the 19th-century Sen. John C. Calhoun and folk singer Woody Guthrie all swimming in the same policy stew.

Just four days after Trump’s inauguration, Brown’s State of the State address took direct aim at the new president’s immigration policies. Brown pledged to “defend everybody -- every man, woman and child -- who has come here for a better life and has contributed to the well-being of our state.” Then he closed his speech by going back to his 1960s roots and quoting Guthrie’s classic. “This land,” he told legislators, “was made for you and me.”

Trump fired back, calling the state’s embrace of sanctuary cities for immigrants “ridiculous” and claiming that sanctuary policies “breed crime.” If California pressed ahead, it could expect to see a draining of federal aid. Scott Pruitt, at the time awaiting Senate confirmation as head of the Environmental Protection Agency, came in for a second shot by refusing to promise he would continue to give California the waivers it needed to operate the state’s tough environmental programs.

The tussle between Trump and Brown right out of the gate is a sign that bigger battles are brewing, not just in California but also around the country. More than 100 mayors, from Austin to Birmingham and Boston to Santa Fe, countered Trump’s initial executive order on immigration with a pledge that they were “united in our commitment to remain inclusive cities.”

States have been challenging federal policy -- even sometimes threatening to nullify it -- for most of the nation’s history. Sen. Calhoun, representing South Carolina, championed such a nullification doctrine in the 1830s, when he attacked a tariff policy that he thought favored the North. He argued that, since the states had created the federal government, they could refuse to follow federal laws they disagreed with. The same arguments drove some of the fiercest civil rights battles of the 1950s and 1960s.

But this time, the winds are blowing from the left instead of from the right. Governors and mayors are pledging to do all they can to stop the Trump agenda. Boston Mayor Marty Walsh is promising to use city hall itself as a fortress if necessary to defend all the city’s residents.

It’s a battle erupting on multiple fronts. In his State of the State address, Brown also said he planned to fight repeal of the Affordable Care Act. Then Brown pledged not to “give in to the climate deniers.” California, the governor said, was prepared to go it alone “to stop the dangerous rise in climate pollution.”

There’s the smoke rising from state legalization of marijuana as well. With the approval of a referendum last November, Maine has joined seven other states (Alaska, California, Colorado, Massachusetts, Nevada, Oregon and Washington), along with the District of Columbia, that have approved the recreational use of pot. That could challenge Attorney General Jeff Sessions, who at his confirmation hearing was asked whether he would allow the states to continue ignoring federal marijuana prohibitions. Sessions danced delicately around the question, saying he “won’t commit to never enforcing federal law.” Sessions has since stated that he hasn’t yet decided whether or not to crack down on pot possession.

Marijuana is only one example of the deepening divide. On many issues the president cares deeply about, state and local governments have an important front-line role. Whether the Affordable Care Act can actually be repealed and replaced will depend, in part, on how much opposition comes from states. The fate of Trump’s immigration policy will turn to an equally large extent on states and cities, because the process of deporting illegal immigrants depends on what local police departments and courts do when they apprehend those without the proper papers. And the states will have a great deal of leverage over climate policy, especially if the federal government pulls back.

This, in turn, frames some fascinating questions. To what degree will federalism prove a bulwark against Trumpism? The president’s opponents would like to see Congress serve as a check on presidential overreaching, but the Constitution gives states much of that responsibility. So states that object to what Washington is doing will ramp up their research on the 10th Amendment -- using it as a weapon of the left instead of the right.

There’s a legitimate question of how much variation among the states the federal government -- and the people -- are prepared to stomach. If California and its Democratic counterparts march hard toward health insurance for all citizens, aggressive climate policies and protection of immigrants, how will the nation deal with states that take precisely the opposite position? This is not only a philosophical puzzle, but a very real policy challenge, since health-care issues, pollution and immigration pay no attention to state boundaries. Some states could prove magnets for people whose problems other states don’t solve -- and some states could end up with environmental problems that blow over entire regions.

In the nonstop narratives that swirled around Trump’s first months in office, these were questions that got little attention. But it’s a safe bet they’ll turn out to be far more important to the new administration’s legacy than the president imagines right now.