Bill de Blasio was at a ballgame in Queens last Sunday afternoon when a group of rural landowners, town officials, Second Amendment advocates and Tea Party activists rallied in the Southern Tier village of Bainbridge on behalf of a radical reform that would dramatically enhance the mayor’s power in his own backyard: a breakup of New York state.

The event hardly constituted a grassroots groundswell for Upstate statehood. But the motivating grievances are real, persistent and not just confined to counties north of the mid-Hudson Valley.

New York City officials have been frustrated for decades by state constitutional limits on their “home rule” powers, including tax policy.

To be sure, there have been plenty of times when governors and legislative leaders have protected New Yorkers from the worst impulses of city politicians — blocking de Blasio’s soak-the-rich income-tax hike last year, for example, and rejecting a financing plan for Mayor Michael Bloomberg’s proposed West Side Stadium a decade ago.

But the state also meddles in city affairs in damaging ways. A current case in point: Gov. Cuomo’s support for a costly union-labor mandate that would significantly reduce the number of new affordable-housing units built under the city’s 421-a property-tax abatements. Cuomo and Senate Republicans also undermined the mayor this spring by lining up with city police and firefighter unions demanding more expensive pension disability benefits.

Upstaters, meanwhile, have their own reasons for chafing under the state’s bridle. Gun owners dislike Cuomo’s SAFE Act. Rural landowners in the gas-rich Marcellus Shale region are frustrated by his ban on fracking. And there’s broad unhappiness with New York’s tax burden and regulatory environment, generally seen as reflecting the big-government preferences of downstaters.

Further stoking Upstate’s sense of powerlessness: Cuomo’s support for implementing a statewide $15-an-hour minimum wage for fast-food workers. The impact on labor markets and business conditions will be most disruptive in upstate regions where the entry-level pay for many production and service jobs is not far above $10.

The two New Yorks — up and down, that is — already have been on sharply divergent economic tracks for years. Only eight states have added private-sector jobs at a lower rate than New York’s 50 Upstate counties since 2009. Downstate, driven mainly by New York City, has had stronger employment growth than all but five states during the same period.

Per-capita incomes in Upstate New York as of 2013 were 4 percent below the national average — and a whopping 29 percent lower than incomes downstate. Upstate local governments and schools effectively are subsidized by the state taxes generated in the New York City metro area — although that hasn’t deterred advocates of a New York breakup.

At least some of the Southern Tier secessionists were willing to acknowledge the multiple constitutional impediments to actually creating a new state. Officials in some border towns, such as Conklin town Supervisor Jim Finch, have talked wistfully of merging into Pennsylvania, while others at the Bainbridge rally suggested splitting the Empire State into self-governing “autonomous regions.”

None of these ideas is actually feasible. But it would not be nearly as far-fetched for disaffected local politicians all over New York to explore ways of amending the state Constitution to broaden their home-rule powers.

They could have a more realistic opening for doing so within the next few years. In November 2017 — coinciding, as it happens, with the next New York City mayoral election — voters across New York will decide whether to hold a state constitutional convention.

A “yes” vote, leading to delegate elections in 2018 and a convention in 2019, would no doubt open a Pandora’s Box of special-interest pleadings on every conceivable issue. Certainly the notion of a more autonomous New York City government would (and should) terrify the city’s business community, in particular.

But if disgust with Albany becomes pervasive enough among New Yorkers across the regional and ideological spectrums, they might just come together to explore ways of moving further apart.