the Vox link about the LA bicycle highway (& more!) is an oldie (2015) but a goodie: https://twitter.com/travis_robert/status/1254455597573066752

the "more" about which I learned via the article includes:

--the 1890s Hotchkiss Bicycle Railroad in NJ (here's a 2012 CityLab piece by @citycalfe : https://www.citylab.com/transportation/2012/08/dodging-cattle-and-bullets-new-jerseys-18th-century-bicycle-railroad/2833/

"The sidepaths of Rochester, Chicago, Minneapolis, and Los Angeles"

( @josephstromberg, author of that Vox piece, cites 2013 paper: "The Sidepath Not Taken:
Bicycles, Taxes, & the Rhetoric of the Public Good in the 1890s" by historian James Longhurst aka @laxbikeguy)

here'a the link to the 2013 paper, in the Journal of Policy History: https://muse.jhu.edu/article/520874 

..but seems like it prob got folded into this 2015 book by Longhurst: "Bike Battles: A History of Sharing the American Road"
http://bikebattles.net/about-the-book/ 

those sidepaths (late 1890s/early 1900s?) evidently inspired by the success of an earlier such piece of 19c bike infrastructure cited in the Vox piece that I'm familiar with: the Coney Island Cycle Path!

aka Ocean Parkway: http://www.nycbikemaps.com/spokes/ocean-parkway-bike-path/

re the history of the Coney Island Cycle Path, the Vox piece links to the website for @carltonreid's 2015 book "Roads Were Not Built for Cars: How Cyclists Were the First to Push for Good Roads & Became the Pioneers of Motoring" https://roadswerenotbuiltforcars.com/coneyislandcyclepath/

(I haven't biked Ocean Parkway in a couple years, but coincidentally we were just talking about doing it all the way down to Coney sometime this spring..now that the kids have finally learned to bike over the past 6 weeks of social distancing!)

..and finally, that California Cycleway, which was intended to connect downtown LA and Pasadena. I recall this 2013 Vice piece by @bcmerchant about it.. https://www.vice.com/en_us/article/bmm4qw/in-1897-a-bicycle-superhighway-was-the-future-of-california-transit

..but see also this piece on LA Curbed by @HadleyMeares just last year: https://la.curbed.com/2019/6/27/18683073/california-cycleway-bicycle-history-transportation

..and Reid's website (and presumably book) has a section on it too: https://roadswerenotbuiltforcars.com/californiacycleway/

Couple addendums to this thread re late 19c/early 20c American bicycle infrastructure, from the authors cited above! https://twitter.com/BikeBattlesBook/status/1254773202913390592?s=19

and this: https://twitter.com/laxbikeguy/status/1254773794285039629?s=19