Aside from a surcharge that partly offsets higher gasoline prices, Chicago has not raised meter rates in nine years. Currently, the base fare is $3.25 to hire a cab, and $1.80 per mile after that. A trip from downtown to O’Hare usually costs about $40 before tip.

Image Credit... Nathan Weber for The New York Times

“I’m hoping the union will attract a significant number of drivers so we can push to finally get a meter increase,” Ms. Chamberlain said. “For too long, the city and the cab companies would ignore what we want — the drivers were helpless because there was no group to speak up for them.”

The A.F.L.-C.I.O. supports the idea of a national taxi drivers’ union as part of its broader strategy to reverse decades of decline in union membership and power. Labor groups are realizing that they can no longer afford to ignore sectors like the taxi industry that employ many immigrant workers, whom unions view as a vital source of potential membership growth. And taxi drivers, whether Ethiopian, Haitian or Pakistani, are often leaders in immigrant communities around the country.

One snag these unionization plans face is that taxi drivers are usually independent contractors who are barred by antitrust law from colluding to set prices (although they can lobby city officials to grant fare increases).

Drivers say that some organizing efforts have been paying off. For instance the 1,200-member drivers’ union in Philadelphia helped secure three fare increases, lower fines for violations like having bald tires and a reduction in the fee for accepting credit card payments to 5 percent of the fare, from 10 percent.

Ronald Blount, president of the Philadelphia union, sees benefits in going national. “We can learn from each other. We can see what forms of pressure worked in other cities,” he said.

If they were successful in forming a national union, the taxi unions would be able to tap the mighty A.F.L.-C.I.O. and its 56 unions to get behind their cause.