Use this form to add data to the database. The webpage will automatically calculate the average location of the data points and find the county where the average observation is located.
About
From the time Colorado began issuing license plates in 1913 until 1999, license plate serials were based on the county of issue. For example, any two-letter, four-number serial with a letter combination that began with an A, B, C or D during the years 1977 through 1981 was issued in Denver county. Similarly, an astute observer could distinguish a plate’s county of issue based on the letter combination of a three-letter, three-number (c.1982-1992) or three-letter, four-number (c.1993-1999) plate.
However, this scheme had a drawback: codes were issued to counties, but when a county grew far faster (or slower) than the rest of the state (as Douglas County did in the 1990’s), that county would run into a shortage (or excess) of plates for that county. To deal with this drawback, the new (since 1999) green-on-white plates are issued without reference to county. Currently, Colorado plates do not yield any easily obtainable information about the plate’s county of issue.
A visit to a state that does indicate the plate’s county of issue (for example, Ohio or Kentucky), one may see a pattern emerge. There is a correlation between county-of-issue and license plate combinations. This is especially evident in smaller counties, where the number of unique letter combinations is limited.
A similar situation exists in Colorado. One may notice a relatively limited set of letter combinations in a given location. As an experiment, I have decided to try to use observations to see if the correlation holds true in Colorado.
History
Since I first began this project in 2008, license plates have undergone numerous changes. I estimate that the state issued enough license plates each year to completely issue two starting letters each year. Some ‘G’ plates were issued in 2003, ‘M’ plates in 2006, ‘S’ plates in 2008, and ‘Y’ plates in 2012. As such, the pool of letters available for the then-issued three-number, three-letter (###-XXX) plates were exhausted in the early 2010’s. Up until this time, Colorado did not issue plates with the letter ‘Q’, but in late 2013 or early 2014, these were added to the pool. This effectively gave the state another year or so with ###-XXX plates (as Q plates could be issues with the Q in each of the positions–e.g., ###-QAA or ###-AQA).
Since Colorado had not issued plates with either ‘Q’ or ‘O’ when it issued XXX-###, white-on-green plates from 1982 to 1993, it was able to issue these letter combinations as green-on-white plates. This provided some additional time, with QXX-### plates being issued in 2016 and OXX-### during the summer of 2017. The state had not issued all possible XXX-### plates from the 1982 series either. My recollection is that (for example) in Denver, BXX plates had only recently been issued when the state moved to the XXX-#### format in 1993. Some of the un-issued plates were used, so there are BXX-###, CXX-### and DXX-### plates out there.
In late summer, 2018, specialty plates with XXX-X## combinations began to appear; base green-on-white passenger plates with these combinations appeared at the end of 2018. Each starting letter appears to last for a year or so, as expected since each starting letter has 26/10 or 2.6 times as many available combinations with the XXX-X## format compared to the XXX-### format.