The licence plate systems used the USA and Canada have seen many changes throughout their hundred-year existence. They were originally introduced in 1903 in the Commonwealth of Massachusetts and the Canadian province of Ontario. Other authorities then began to follow their examples, eventually making the display of licence plates a requirement across all states and provinces by 1918.

Originally, the plates were made out of rubber, iron, leather or porcelain, with the letters and numbers being simply painted on. Most included an abbreviated state identifier and year number at one side, which enabled the police to check on sight that the vehicle registration was up to date. As result of this feature, each year, citizens had to obtain new plates from the state government. The colours changed from year to year, which again helped the police to identify out of date registrations.

The types of materials used in the manufacture of licence plates have changed through the years, but today the majority of states use metal, which is embossed with the registration number. However, several states have now overhauled their systems to digitally produce their licence plates.

Over the years it has also become common for state plates to display slogans. Examples are the Nova Scotia plates, which read “Canada’s Ocean Playground” or the political statement on Washington D.C. plates, which states “Taxation Without Representation”. Even more recently, website addresses have started to appear on some plates.

The construction of licence plate numbers varies between states, though most do not use the letters I, O or Q. Some issue registration numbers that are valid for as long as the person stays within that state, while others change their registration numbers periodically. If a person moves to a new state, they will usually be required to obtain a new registration number.