Read an interesting article on the San Jose Mercury's Mr. Roadshow column about the apparent removal of the green-on-white mileposts along Kern County freeways. I have to assume the freeway in question is CA-58 east of Bakersfield. The mileposts were originally installed only along the Mojave Bypass when the freeway was constructed. Over time, the mileposts were extended east to Boron and west to just outside Bakersfield.
Gary Richards states...
"There are no longer any milepost markers on California highways. A few were installed on Kern County freeways about 10 years ago but they were recently removed. (They created confusion when it came to responding to roadway incidents.)"
AFAIK, the CHP, Caltrans and local law enforcement continue to use postmiles to locate roadway incidents so one could see how things could become confused if a milepost number is given to a 911 dispatcher. The simple solution for Caltrans was to remove the mileposts.
I will be driving that stretch of CA-58 in late October so I can confirm whether the mileposts have been removed or not unless someone else beats me to it.
Link to the Mr. Roadshow column... http://www.mercurynews.com/2016/09/08/roadshow-lawrence-expressway-changes-coming-at-i-280-off-ramp/
(you'll need to scroll down to find the relevant question and answer)
FWIW, California's postmiles are black-on-white paddles that contain the route number, county code and mileage from the county line. Mileposts, on the other hand, are white-on-green paddles that measure the distance from the route's southern or western terminus.