By virtually every indicator, 2007 was a dismal year for American workers. Job growth slowed, unemployment jumped and wages lost what little ground they had gained against inflation since 2003. There is one sliver of good news: the percentage of American workers who belong to a union rose for the first time in three decades.

The Labor Department reported that the number of workers belonging to a union grew by 311,000 to 15.7 million. That means union members increased from 12 percent of the American work force in 2006 to 12.1 percent last year. In the private sector, unions’ share of workers inched ahead from 7.4 percent to 7.46 percent. While the rebound is tiny, and might yet prove to be a statistical mirage, it is the first recorded increase in organized labor’s ranks since the 1970s, when almost one in four workers belonged to a union.

There is little doubt that American workers need unions. Wages today are almost 10 percent lower than they were in 1973, after accounting for inflation. The share of national income devoted to workers’ wages and benefits is at its lowest since the late-1960s, while the share going to profits has surged. The decline in unionization has been a big part of the reason that workers have lost so much ground.

The future of organized labor is not cause for great optimism. Employers have become more aggressive about keeping unions out. Competitive pressures from globalization, deregulation and technological change have resulted in the loss of many union jobs.

Indeed, unionization rose last year partly because of the slow pace of job creation in nonunionized sectors of the labor market. The jump in unionization rates in the construction industry, for example, was partly attributed to the steep decline in residential construction, where there are fewer unions, while the more heavily unionized commercial construction sector remained strong.

Still, the uptick offers hope that the renewed emphasis on organizing workers by some of the nation’s largest unions - like the service employees’ union, the Teamsters and others that split off from the A.F.L.-C.I.O. to form the Change to Win coalition - might start paying dividends despite the difficult odds.

A bill that would have made it easier for unions to organize workers died in the Senate last June. Congress should take up this issue again to stop companies from using threats and other aggressive tactics to keep organized labor out, and to help win workers their rightful share of the economic pie.