I am proud to be a card carrying member of Local 32035 of the Communications Workers of America.

It was not always thus. The Washington Post is an open shop, and I dropped my membership several years ago when the union was encouraging readers to cancel their subscriptions to protest some management action. I didn’t see much sense in paying dues to accelerate the destruction of the newspaper business.

I don’t expect to gain much personally from rejoining the union faithful, because I’m in the top decile of American wage earners that has prospered in recent years. I signed up because income inequality, after years of worsening, has reached a crisis — and the decline in union membership is partly to blame. Rejoining the labor movement is my small, symbolic protest.

The gap in wealth and income between rich and poor is the worst since the Great Depression, and the gap between the rich and the middle class is at its highest since the government began keeping such statistics 30 years ago. After more than three decades of income growth for the wealthiest 10 percent and stagnation for everybody else, the top 3 percent now have more than twice as much wealth as the bottom 90 percent.

And Americans are angry about it. The percentage of Americans who believe you can get ahead through hard work has declined about 15 points over the last 15 years, according to polling by Gallup and the Pew Research Center.

There are many causes of growing inequality — globalization, education disparities, tax policy — but an International Monetary Fund study released in March found that the decline in union membership has been responsible for half of the rise in the share of income going to the top 10 percent of earners in advanced economies between 1980 and 2010. Declining union membership, by weakening the bargaining power of low- and middle-income workers at both union and nonunion businesses, has increased the share of wealth going to corporate higher-ups and shareholders.

Straws in the wind suggest a building backlash. Last Tuesday, Los Angeles voters approved a $15 minimum wage, joining more than 17 states and several municipalities that have agreed to raise their minimum wages since 2013. Fast-food and retail employers, under pressure, have announced increases in low wages covering at least 2 million workers.

Organized labor, in retreat for decades, has been reasserting itself within the Democratic Party. Last week, Philadelphia Democrats chose as their next mayor Jim Kenney, who had strong union backing in the primary (and faces only token opposition in November). The come-from-behind victory for Kenney, who had been outspent 3 to 1, follows similar long-shot wins for union-backed mayoral candidates in Boston and New York.

In Washington, D.C., pro-union Democrats, defying President Obama, put up a tougher-than-expected fight on Trade Promotion Authority legislation in the Senate, and it’s not clear that free-trade bills will pass the House.

Union membership, thanks to the likes of Scott Walker, continues its long decline, but impressions of labor have improved. Just four years ago, a plurality of Americans had an unfavorable view of trade unions, but now the impression is 48 percent favorable to 39 percent unfavorable, according to Pew. Across the country, some 5 million workers are negotiating contracts this year, the largest number for collective bargaining in several years.

“They’ve been beaten down so much over the years that these American workers thought not losing was winning, so they didn’t have any expectations,” AFL-CIO President Richard Trumka told a group of Post journalists recently. “They’re getting way past that right now and they have expectations, they have demands, they have beliefs that they’re entitled to more.”

Trumka likens the moment to the Pullman strike of 1894, when workers, seeing their earnings shrink to starvation levels after an economic depression, finally pushed back. “That’s like the point where we’re at right now in this country: People are p—-ed,” Trumka said.

That may be wishful thinking. But the obscene gap between the rich and everybody else pushed me to reconcile with the union movement. My late grandfather was a labor lawyer and chief counsel to the Seafarers and other unions; he taught me about collective bargaining over the dinner table. When I eulogized him after his death in 1997, I observed that his life had followed the arc of the labor movement: It peaked at midcentury when he was in his prime and declined late in the century, as he did.

Eighteen years after his death, we can all see and feel the consequences of labor’s demise. For me and, I hope, for others, it’s time for a homecoming.

Dana Milbank is a Washington Post columnist.