Maine hasn’t been part of Massachusetts since 1820 — or, if you prefer, Massachusetts hasn’t been part of Maine since then. Yet the two states, once a British colony together, maintain a symbiotic relationship.

Maine benefits from its proximity to Greater Boston, hub of the New England economy. The tourists who flock to Maine and become seasonal, or permanent, residents are more often from Massachusetts than anywhere else. And we have a lot of open space and splendid scenery that keep our neighbors coming back.

States are more often presented as rivals than collaborators. Yet two new proposals brewing in Massachusetts could produce major benefits to Maine.

The first is a discussion between former Democratic Gov. Michael Dukakis and current Republican Gov. Charlie Baker about passenger train service. Baker wants to expand South Station, which is operating beyond capacity, thanks to commuters’ discovery that they don’t need to drive to work.

Dukakis, who once chaired Amtrak’s board and dramatically improved Boston’s transit links when he was governor, prefers a different, and older, idea — linking South Station to North Station, which also would allow uninterrupted travel between Maine and the rest of the East Coast.

The train tunnel was once part of the “Big Dig” that put the Central Artery underground and connected the Massachusetts Turnpike to Logan Airport. Maine’s Sen. George Mitchell, then majority leader, obtained funding that would have opened the tunnel about the same time Downeaster service began to Portland. Unfortunately, as project costs rose, the tunnel got squeezed out, but it’s every bit as feasible now as it was 20 years ago, and needed more.

The Massachusetts governor and former governor will go a few rounds, but ultimately it makes sense to provide the tunnel and upgrade South Station, though perhaps not on the palatial scale Baker envisions.

What would this mean to Maine? A dramatic improvement in rail service. It’s forgotten now, but back when the tunnel was in prospect, Canadian provinces, including New Brunswick and Nova Scotia, were planning direct rail service through Boston as far as New York.

As we’ve seen with the Nova Star ferry to Portland, Canadians, unlike Americans, are willing to provide generous subsidies for public transportation. If Canadians want to run passenger trains, then many Maine stops, possibly including Bangor, Lewiston, Waterville and Augusta, become feasible.

The second development that could benefit Maine is an effort by unions and progressive groups to amend the Massachusetts Constitution to allow a higher income tax rate on millionaires. Despite its reputation as the nation’s most liberal state, Massachusetts is in the curious position the federal government was before passage of the 16th Amendment in 1913, allowing a progressive income tax. Massachusetts can have only a flat tax, currently 5.15 percent.

Massachusetts is effectively a one-party state, despite some Republican governors, and Democrats at the Legislature are notoriously hostile to progressive change. They beat back a graduated tax amendment in 1994, which was, admittedly, a terrible time for the plan, with the Bill Clinton tax increases of 1993 still in everyone’s mind — and before the increases demonstrated their positive effect on wages and the overall economy.

So amendment by referendum is the only way to go and, in Massachusetts, it takes three years to get on the ballot. This plan is simpler than the last one — a single, higher bracket, 9 percent, on incomes more than $1 million. It would raise considerable revenue from people who could easily pay more in taxes.

The significance for Maine becomes apparent when you consider the effect of the 5.15 percent flat tax on perceptions at the State House. Democrats and Republicans here agree on little else, but they are united in believing our income tax rate is too high. They’re wrong, but the consensus is based on the comparison with Massachusetts. If that state had a 9 percent rate, the apparent need to reduce Maine’s income tax would vanish.

And it’s about time. The current plan to reduce the top rate to 7.15 percent, a major boon to the wealthiest taxpayers, is funded by increased sales taxes, which bear most heavily on the lowest income Mainers. At a time when blue-collar jobs pay less, and the wealthy are the only ones whose share of state income is rising, we need to reverse course.

Better train service and a fairer tax system would improve life in Maine for all of us. Although we don’t have a direct vote on these matters, we should at least provide some encouragement and moral support.

Douglas Rooks has covered the State House for 30 years. Email at drooks@tds.net