siliconwafer writes "The US Department of Homeland Security (DHS) is looking to acquire a vehicle license plate tracking system, to be used at the national level. According to the solicitation obtained by the Washington Post, commercial readers, supplied by a private company, would scan the plate of vehicles and store them in a "National License Plate Recognition" (NLPR) database. This is already being done at the state level, and privacy advocates are up in arms, with EFF and ACLU suing California over their automatic plate readers. Now that this has potential to become a broad and national program."
[ED Note: "Shortly after the Washington Post broke the story on the national plate reading system, it appears the DHS has shelved their plans for the tracking system, by order of Homeland Security Secretary Jeh Johnson, at least in the interim."]
Not just colors, but other design elements too. For example, the Texas plate has an outline of the state of Texas and a silhouette of a cowboy on a horse.