Warring between mayors and governors is as natural in New York as jaywalking. But the tough-guy act performed, each in his own way, by Gov. Andrew Cuomo and Mayor Bill de Blasio is singularly corrosive because the welfare of nearly six million daily subway riders is at stake. It is shocking how little progress on bridging differences has been made since the governor declared a state of emergency seven months ago. It feels like “Groundhog Day,” only far less entertaining, with the same points made over and over.

Each side seeks to bolster its case by hauling out documents so old and long-ignored that they are about as relevant to this emergency as the Dead Sea Scrolls. Each also has a knack for getting under the other’s skin, needlessly so.

Mr. de Blasio’s representatives stopped the M.T.A. board from approving, for now, a billion-dollar plan to spruce up 33 subway stations with countdown clocks, better lighting and other amenities. Frills, the mayor implied. Spoken like someone who doesn’t appreciate how tired riders are of stations that look like the ruins of Stalingrad.

For his part, Mr. Cuomo has elbows sharper than Freddy Krueger fingers, and he keeps swinging them. He proposed creating special tax districts in neighborhoods where property values go up because of new transit projects like the Second Avenue subway. The goal would be to “capture” increased property tax revenue to benefit the M.T.A.

The concept is not without merit: If real estate is worth more because a subway is nearby, why not peel off some of the wealth to keep the rails in shape? But in typical fashion, the governor went off on his own, suggesting this without first clueing in the mayor and his aides, who need that same revenue for their own budget. Naturally, they pushed back.