Los Angeles County voters on Tuesday approved a tax to expand its mass-transit network. Pictured here: The new Expo Line pulling into Santa Monica in May. (Al Seib / Los Angeles Times)

There’s really no other way to put it: Los Angeles on Tuesday threw off its typical and longstanding ambivalence about whether it wants to be a big city and definitively embraced a more urban future.

In giving the Measure M transit tax roughly 70% support, a full 3 percentage points above the super-majority it needed to pass, county voters virtually guaranteed that L.A. will finally build the mature, comprehensive public transit system it has been working toward, often haltingly, since the 1980s.

There is plenty of money for roadway improvements in the measure, but a remarkable $860 million in estimated revenue each year will be earmarked for mass-transit projects. Some are ambitious enough to radically remake the region’s public transportation map.

Another countywide proposition, Measure A, passed with an even higher margin, earning more than 73% of the vote. It will boost investments in park space and could accelerate plans to open much of the Los Angeles River to public access. (Measure M will help do the same, in part by funding improvements to the network of bike paths along and leading to the river.) And make no mistake: A city with more open green space is a more urban and public-minded city, one at long last moving beyond the radical privatization that accompanied postwar growth in much of Southern California.

A $1.2-billion city bond measure to build new housing for the chronically homeless, Proposition HHH, passed with exceptionally strong support, gaining 76% of the vote.

In Santa Monica, voters decisively rejected the aggressively anti-urban Measure LV, which would have (among other curbs on construction) required a public vote to approve nearly any new building higher than 32 feet. Yes, readers of mine from out of town, you saw that right: Had the measure passed, those mammoth, marauding four-story skyscrapers now threatening to overwhelm Santa Monica would have been banned except where green-lighted by special referendum.

It remains to be seen what these results will mean for L.A.’s own Neighborhood Integrity Initiative, which will appear on the city ballot in March and calls for restrictions on development and new housing that are — if not quite as extreme as LV’s — certainly as clear in their desire to shape Los Angeles along fundamentally suburban lines.

Still, the idea that L.A.’s core identity is wrapped up in the car and the single-family house — a notion that has been both crumbling and rather desperately defended by nostalgic readings of the city in recent years — took the sort of hit from which it may never recover. This is especially true given the margins Tuesday, with Measure M’s 69.8% support surpassing even the 67.2% that an earlier transit tax, Measure R, gained in 2008 and Measure LV winning just 43.8% of the vote in Santa Monica.

That definition of the city has always been at least partly a fiction in any case, given both the realities of regional demographics — one recent study found that L.A. has a higher proportion of renters, at 52%, than any city in the country, with the percentage in Santa Monica even higher, at about 70% — and the history of urban development here. But for whatever reason, we seem to have a collective amnesia about the character of prewar Los Angeles, finding it all too easy to forget about the reach of the L.A. streetcar network in the first half of the 20th century and the power and volume of early experiments in moderately dense multifamily modernist housing by architects including Irving Gill, R.M. Schindler and Richard Neutra.

This is perhaps the most important message sent by voters Tuesday: The Los Angeles dominated by the single-family subdivision and the freeway overpass is not some permanent, fixed city. It was preceded by a different kind of city, one deeply reliant on mass transit and active in building cooperative and multifamily housing. The results on Tuesday suggest there is little doubt now it will be replaced by a noticeably different kind of city as well.

This emerging city — which I have referred to as the Third Los Angeles, following the prewar First L.A. of the streetcar and the bungalow court and the Second L.A. of the freeway, the concrete-lined river and the glamorous detachment of the single-family house — will continue to be challenged and even attacked by supporters of what for many powerful people in Los Angeles has been a remarkably generous status quo.

The residents who have benefited for the longest period of time and most directly from the largesse of Second L.A.-era policies have much to protect and will use their significant resources to protect it. They have been aided not only by low property taxes and the mortgage-interest deduction but various caps on the supply of new housing in L.A. County, which has caused residential property values in some neighborhoods to leap 30- or 40-fold or even higher since the 1970s.

The most extreme version of their rhetoric is not so different from Donald Trump’s promise to “Make America Great Again”; it depends after all on the notion that Los Angeles, as it grows taller, denser and more urban, is in danger of losing some fundamental part of its traditional civic identity or perhaps has already lost an appreciable chunk of it.

Nor is it a stretch to see the opponents of new housing and foes of transit spending as close and perhaps natural allies. A main backer of the Neighborhood Integrity Initiative, the AIDS Healthcare Foundation, donated $10,000 to the campaign to defeat Measure M.

But cities, if they are to be living and not dead, vital and not vast museums, have an obligation to plan for a range of futures: to consider the needs of residents not yet here or not yet born as well as those already established here. (This is true even in cities like Los Angeles where population growth has markedly slowed.) On a day when the rest of the U.S. rallied on behalf of an America that in demographic terms is fading from view — and there is no way to ignore or sugarcoat that fact, given that Trump’s support was highest in the whitest and oldest sections of the country — it was encouraging, a small but significant comfort, to see voters in Los Angeles send a different message.

In that difference — and in the increasingly stark electoral gap between large metropolitan regions and the rest of America — lies what is sure to be a dominant story line for U.S. cities over the next four years. Despite being a lifelong New Yorker (and a developer of tall buildings, no less), Donald Trump ran explicitly against big cities and multiculturalism and by extension against cosmopolitanism. That message proved hugely appealing in rural and small-town America.