California’s middle-mile backbone, and what it changes for fiber

In July 2021, Governor Gavin Newsom signed Senate Bill 156 into law and put $3.25 billion behind an idea that had been stuck in the “someday” column for a decade: a publicly owned, open-access middle-mile network reaching across California. Five years on, the project is real enough to have a statewide route map and a committee watching every mile of it. It is worth understanding what was actually built — and what it deliberately leaves to companies like us.

What “middle mile” actually means

The middle mile is the backbone. It is the high-capacity fiber that carries large volumes of data at high speed over long distances, connecting regions to the wider internet. It is not the connection that reaches your building. In network terms, the middle mile gets traffic to the edge of a community; the last mile carries it the rest of the way to a home, a clinic, or a warehouse loading dock.

California’s initiative is built on an open-access model, which is the part that changes the economics. Any qualified provider can connect to the backbone on equal economic and service terms. The state is not picking a single winner to resell capacity — it is building shared infrastructure that municipalities, Tribes, and independent ISPs can all reach.

• Open access. Multiple providers connect on the same terms, rather than negotiating with one incumbent that owns the only route into town.
• Technology-neutral. The program does not mandate a single delivery method, so the backbone can feed fiber, fixed wireless, and other last-mile builds.
• Oversight. The Middle-Mile Advisory Committee monitors design and construction, and the California Department of Technology leads implementation.
• Targeted. Routes were planned to reach the unserved and underserved communities the private market had skipped.

A backbone reaches the edge of a community. Whether anyone in that community gets online depends entirely on who builds the last mile.

Why a backbone alone connects nobody

Here is the part that gets lost in the press releases. The middle-mile network does not, by itself, light up a single home or business. It is the on-ramp, not the driveway. A rural town can have state fiber running past the county line and still have residents on the wrong side of the digital divide, because the expensive, unglamorous work of building from the backbone to the premises is a separate job — and a separate investment.

That is the work the open-access design is meant to unlock. By removing the cost of the long-haul backbone from the equation, the state makes last-mile builds pencil out in places that never did before. For operators who actually own and run fiber plant, that is the opening: a publicly funded backbone lowers the barrier, and the providers willing to dig the final stretch turn it into service.

We read the middle-mile initiative as exactly that kind of opening. The state has committed billions to the part that connects regions. The part that connects buildings — engineered, owned, and supported by a provider who answers for it — is still where the real connection happens.