signage. Subsequent to the launching of Battenburg markings on police vehicles in the 1990s, the police introduced retro-reflective versions of the Sillitoe tartan markings to their uniforms, usually in blue and white, rather than the blue and yellow used on vehicles. Many police forces have a sky blue and white Sillitoe tartan hatband as part of their PCSOs uniform. This is as a result of moves by the trade union Unison to develop a national law enforcement uniform within the UK. As a result of this the blue and white Sillitoe tartan has been taken up by a number of municipal organisations, including the London Borough of Newham Law Enforcement and Nottingham City Council Community Protection, who are accredited under the Community Safety Accreditation Scheme. It is also being taken on by a number of private security organisations (most notably Canary Wharf Security) to project the attributes of public law enforcement. United States Only a few police forces in the US have adopted the chequered pattern: the Chicago Police Department, Cook County Sheriff's Police and Brookfield Police in Illinois, Forest Park Police and Evergreen Park Police in Illinois, Hillside Police in Illinois, the Washington, D.C. police, and the Pittsburgh Police. U.S. police departments prefer to use a two-row pattern, instead of the three-row pattern common in Europe and Australasia. Many other departments in the United States and Canada, while lacking the tartan on their cap bands, have begun using two-row reflective versions as part of the design on high-visibility outer garments and vests. Chicago Police Department's pattern is dark blue and white for patrol officers and detectives, and dark blue and gold for sergeants and higher ranks. Sillitoe tartan caps were introduced in 1967. The band is around not only the department's service caps, but winter knit caps, summer baseball-style caps, the campaign hats and horse bridles of the mounted unit, bicycle helmets, and dog collars as well; it is not worn on the fur trim winter hat nor the light blue riot and motorcycle helmets. The Chicago Police also use the pattern on some signage, graphics, and architectural detail on newer police stations. The police of Brookfield, Forest Park, Hillside, and Evergreen Park follow the same colour protocols as nearby Chicago, although Evergreen Park and Hillside use black rather than dark blue, in keeping with their uniforms. The Pittsburgh Police use a dark navy blue and gold pattern, in