So it was no surprise when, just days ago, the 2020 Republican National Convention looked like San Antonio’s for the asking.

And then, the Alamo City said it would not ask.

The potential economic juice, the mayor and council concluded, was just not worth the certain political squeeze.

Salivating chamber of commerce types were told they’d have to wait for a safer opportunity, one that would not guarantee clashes between thousands of nationalist base voters in the convention hall and many thousands more infuriated Americans out in the streets.

The story does more than highlight the differences between the nation’s polarized state of mind and the more complex cultural and political life of the third biggest metropolitan area in Texas, which is by far the biggest metro area in the nation with a Latino majority — 56 percent, almost 1.3 million, and climbing steadily.

It also speaks to questions getting pondered increasingly on Capitol Hill, at party committee headquarters and along K Street: Is the time past when presidential conventions are guaranteed to infuse the gross municipal product of one lucky city without any downside? And in an era where the standard-bearers are predetermined and security precautions must be over the top, is it wise to devote a whole week every four years to what’s effectively a trade show for political industry insiders — with just one night of prime-time exposure for the nominee?

In addition, of course, San Antonio’s spurning of the GOP convention is the latest reminder of how virtually every venerable civic institution becomes contentious the moment the incumbent president enters the picture.

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The color purple

Bexar County, with San Antonio its anchor tenant, has doubled in population just since the early 1980s while remaining a presidential bellwether. The winner carried the county in 11 consecutive elections before Hillary Clinton thumped Trump by 13 points. The result underscored how a burgeoning Hispanic electorate has put the region on the leading edge of the demographic shift that’s turning Texas politically purple — and is destined to make it blue sometime in the next two decades. It also was fresh evidence the GOP does not mend fences with Latinos at its peril.

San Antonio was told it would have to come up with $70 million (some public funds but mainly corporate donations) to spend playing the generous host — plus tens of millions more for security, which Congress has always covered in the past but isn’t required to.

The anticipated return would be at least $200 million in hotel bookings, restaurant tabs, taxi rides and T-shirt sales.

The city formally bid for the GOP gathering that went to Houston in 1992, the Democratic confab that was in Chicago instead in 1996 and the Republican convention that ended up in Philadelphia in 2000.

Economists at the College of the Holy Cross, in Massachusetts, studied every convention from 1972 and 2004 and concluded they had “no discernible impact” on host city jobs or income. (The same professors more recently concluded that hosting the Olympics is a consistently bad investment.) But separate studies after the 2016 conventions found GOP host Cleveland and Democratic host Philadelphia both made decent money.

None of those gatherings, though, were remembered for the sort of violent televised protests in 1968 that hobbled Chicago’s convention and tourism industries for decades — and just the sort of clashes already being contemplated by anti-Trump groups, no matter where he goes to get nominated for a second term. Going to San Antonio, just 150 miles from the Rio Grande, would have particularly inflamed Hispanic voters angry at the president’s drive for a border wall, his description of Mexican “rapists,” his ending the program to shield so-called Dreamers from deportation and his castigation of trade policies that have fueled the economy of South Texas.

“Cities don’t want him,” former Mayor Phil Hardberger told reporters after members of the GOP site selection committee first visited in March and made clear it was because other places had turned them down. “I don’t think this would be good for San Antonio either, because of the drumbeat of racism that he’s promulgated.”

But the current mayor, Ron Nirenberg, insisted that financial pros and cons were all the city council discussed, for almost three hours behind closed doors May 3, before backing away from a bid. And, in an expansive sense, he could have been speaking the truth: Partisanship and short-term balance sheets aside, a cacophonous convention centered on such a polarizing figure might curdle the reputation of a city where one in eight jobs is connected to the hospitality industry.

Of course, Brad Parscale, who is the president’s re-election campaign manager after running Trump’s 2016 digital strategy from his San Antonio office, does not see it that way. “A city council of left-wing activists destroying the economy of #SanAntonio,” he tweeted. “@Ron_Nirenberg and city council just made the business community their enemy. Have fun with that.”

That prompted this similarly sharp response on Twitter from another former mayor, Julián Castro, the former Housing secretary whose twin brother is Democratic Rep. Joaquin Castro of San Antonio: “The Trump campaign is so SCARED of losing Texas in 2020 that it is DESPERATELY trying to get San Antonio to bid for the RNC convention as political insurance. It won’t work, Brad. RNC loses millions for its hosts. And you’re going to lose Texas anyway in 2020.”

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Convention wisdom

Those echoes of Trump’s combative style point to the question of whether presidential candidates — especially those with brands so reliant on Twitter outbursts — can benefit in the social media age from the traditional four days of carefully sequenced made-for-TV convention testimonials.

Three of the last six conventions were truncated to three days: Hurricanes prompted Republicans to call off their Monday sessions in St. Paul, Minnesota, in 2008 and Tampa, Florida, in 2012, and the Democrats chose not to meet in Charlotte, North Carolina, on Labor Day 2012. None of the convention organizers reported regretting those decisions.

The final night of the conventions, when the nominees have unfiltered access to the country when delivering their acceptance speeches, draw significantly more viewers than all other nights.

But in 2016, the expected ratings bonanza expected from the GOP meeting did not materialize. Trump’s 75-minute “I alone can fix it” stem-winder drew 32.2 million viewers, by Nielson’s count, just 7 percent more than Hillary Clinton’s speech the following week and 6 percent more than Mitt Romney’s acceptance speech in 2012.

How many people will want to absorb another speech like that in two years is uncertain. Moreover, the scene for a week in the convention city is a transported, condensed but intensified version of the Washington “swamp” culture from which both parties profess interest in creating distance.

Paring back the insiders’ schmooze fest, and the formalities inside the hall, could make sense in the name of modernizing the image of today’s politics — even if a more streamlined system could make the economics and politics of playing the host city even more tenuous.

Four years ago, eight cities submitted formal bids to host the GOP. Now that San Antonio is out, the only cities known to be under consideration for 2020 are Las Vegas (which only got in the hunt this month) and Charlotte. A decision is due by July.

Last week, Democratic National Committee officials let slip that eight cities have applied to host the challenger’s convention: Atlanta; Denver; Houston; Miami Beach, Florida; Milwaukee; New York; San Francisco; and Birmingham, Alabama. That selection isn’t expected for a year.