Congressional tour guides and visitors’ assistants voted Friday to unionize for the first time in the guides’ 134 years of existence.

The decision to form a union geared toward improving guides’ working conditions comes after months of complaints about poor management practices, unclear benefits and a punitive atmosphere since the Capitol Visitor Center opened and the Capitol Guide Service was transferred to the Architect of the Capitol in 2009.

“With the new management, we’ve seen a lot of changes that haven’t been for the better since moving under the AOC,” said one longtime tour guide and member of the union organizing committee, who is not authorized to speak to the media. “We’re very much looking forward to making some positive changes.”

Nearly 70 percent of the 138 Capitol Visitor Center guides voted to form the union under the American Federation of State, County and Municipal Employees, and 94 percent of the guides voted.

Carl Goldman, executive director of AFSCME Council 26, said the union membership will not be mandated, but it will be encouraged.

“Higher membership helps us more effectively deal with the issues they care about,” Goldman said. “We try to convince people that we’ll do a better job, that we’ll have more respect from management and also more resources to do the job if more people are members.”

And while the guides may have been celebrating their success Friday, they’ll have a lot of work to do in the coming weeks.

After being certified by the Office of Compliance, the union must organize its own local chapter, write a constitution and elect and train officers — all while working with management to immediately improve their workplace.

“We’re interested in having a cooperative relationship with management,” Goldman said. “There are people in management who we started the dialogue with and I think we are going to be able to settle some of the issues.”

CVC employees filed a petition to unionize in June citing complaints of overpacked theaters, unsanitized headsets and no allotted research time.

They’re required to wear the same wool uniforms rain or shine and can’t use water bottles outside, they said.

Employees were further disillusioned when a CVC supervisor recently decided to throw out a bag of white powder labeled “anthrax” without first calling police.

One employee said the system for alerting them to any potentially dangerous incidents in the CVC is inefficient because they are notified over their radios, which they can’t listen to constantly while they speak on tours.

In July, Terrie Rouse, the CVC’s CEO for visitor services, was dismissed after a three-year stint marred by standoffish relations with Members and employee discontent.

The Transportation and Infrastructure Subcommittee on Economic Development, Public Buildings, and Emergency Management, which oversees the CVC, intends to invite union representatives to its scheduled Sept. 30 hearing about Capitol safety and security concerns, said subcommittee spokesman Jim Berard.

Eva Malecki, spokeswoman for the AOC, declined to comment.