In 2017, some major changes happened to the design of Mexican license plates.
They were simplfied and standardized, and all of the states were required to change their plate designs to confirm to the new standards.
The new "rules" for Mexican plates are outlined in a document from the SCT - Secretary for Communications and Transport - the standard is published every few years in the DOF (Diario Oficial de la Federacion) - a Mexican government document. Periodically, there are sections in the DOF documents which outline the new plate numbers (that's where I get my information on numbering) and it also contains information about the plate specifications - how they're made, sizes of letters and numbers, spacing, thickness, and other technical data.
In the June 2016 version of this document, there is a new specification about how the plates should look ... what elements can go in what places, where graphics can be, and more importantly, where they CAN'T be. Starting in late 2016 and early 2017, several states have changed their current bases, or created completely new bases, to comply with the new standard.
Below is a diagram of the new standard plate. This picture originally came from the DOF document, but I made the text bigger, and added the English translations and the hologram images.
The elements of the plate are, as defined in the picture above:
The 2017 CDMX plates have an angel hologram in the background along with the SCT and manufacturing center marks, so variations are certainly possible. The 2019 Tamaulipas plates have the "Tam" wordmark going across the entire plate in a reflective hologram.
By the end of 2017, all but 4 states (MICH, OAX, PUE, TAMPS) had issued new plates.
Oaxaca issued new plates in 2018, and Tamaulipas in January 2019. Now, all of the states except Michoacan and Puebla have changed their plates to follow the new standard. It seems there was some leeway, and because the MICH and PUE plates do not have any graphics over the numbers, it looks like they are allowed to wait for their next general replate to make the required changes.
Several states are already on their second "new-style" plate issue - and Coahuila's new graphic is coming out in 2019.
Motorcycle plates have also changed - growing from their microscopic size of 150x100mm to their new size of 215x134mm. This is about 8½ x 5¼ inches - which is bigger than the 7x4 inch size of American cycle plates.
They are also incorporating the new elements seen on passenger plates - the (T) for Trasera in the top left, the country and state coats of arms, etc.
The diagram to the right is originally from the DOF document, but I took away some extraneous measurements and added the A0AA0 registration number. Theoretically, with the size of these motorcycle plates, they can accommodate 6 - or even 7 characters, so the ranges for motorcycle dealers from the 2013 and 2016 specifications (Y001AA - Z999TZ) will now fit on a cycle plate.
As with the passenger plates, states are now mostly converted to the new bigger motorcycle plates.
Check out the individual state pages to see the changes since 2017 ... now that almost all states have changed over, it's redundant to have all of the new designs here on this page.