cool things with wheels, since 2006
Diagonal parking helps keep cars from poking further into the street and back in parking reduces accident potential when leaving the spot. This was used often in small towns with narrow (horse and buggy) streets.(There is one in every crowd.)
Syracuse NY has a few back in diagonal parking. Technically in NYS its illegal to back out into traffic (a public street)... Even from your own driveway... With this diagonal parking, you can get more cars parking on the street in any particular area over parallel parking...
This has been in use in Austin, Tx. for a few years now.
A couple of cities near me in Ohio have just started this in the past few years.
We have diagonal parking in Owego, N.Y. and Binghamton, N.Y. right on the main drag.
As far as I know all diagonal parking in Tucson is back in only.