"Meter Maid" was used in Salt Lake City and Denver before New York. "Brownie" might be all ours, though.
1960, June: In order to address the mounting parking problems at parking meters, the Commissioner of the New York City Traffic Department institutes a civilian enforcement program whose field forces were staffed exclusively by women. Given the title of Parking Meter Attendant, they are empowered to enforce only violations of parking regulations at meters (hence the popular term "meter maid".) The NYPD continues to perform all other traffic enforcement. The first group of 100 Parking Meter Attendants are required to have a high school education and are given two weeks of training, including some training in jiu-jitsu for self-defense. In the first six months of the program, more than 200,000 summonses are issued. The fine for a summons is $5.00.
1990: A new Traffic Enforcement Agent uniform is introduced. Prior to this change, the Agents uniform had been brown, and were commonly referred to as 'brownies' by the public. Intended to improve their image and do away with the brownie label, the new uniform is a navy blue jacket with gray slacks.
10 January 1956, Reno Evening Gazette, pg. 2:
DENVER, Jan. 10.--Denver plans to hire eight "meter maids" - women in uniform who will check downtown parking meters for overtime violations.
19 December 1956, Hammond (Ind.) Times, pg. B-2:
Meter Maids Are Tough
At various times we have told of efforts in several cities to shift part of the load of enforcing traffic rules upon feminine shoulders. Trial runs here and there had shown good results and now Salt Lake City comes through with enthusiasm over the way the women have worked in the two years that Meter Maids have been used.
The first Meter Maid patrol was formed in July, 1954, with the intention of having women take over the checking of parking meters. They were authorized to hand out tickets for overtime parking, improper parking, lack of proper vehicle registration and also to keep watch for stolen cars.
18 June 1981, New York Times, pg. B3:
The frowing number of assaults against the agents, commonly known as "Meter maids," or "brownies" from the color of their uniform, comes at a time when the Koch administration has initated several programs to alleviate midtown traffic congestion.
9 October 1984, Gettysburg (PA) Times, pg.11:
"We'll chase anything," boasts Traffic Commissioner Samuel Schwartz, who personally leads this posse to get a first-hand look at the problems faced by his traffic agents, nicknamed "brownies" for the color of their uniforms.