BY A RAZOR-THIN margin, Massachusetts voters rejected Question 7, the ballot measure that would have capped minimum lot size requirements for single-family homes at 5,000 square feet.

This commonsense reform could have unlocked thousands of new homes. Estimates ranged from a conservative 750 a year to more than 5,000 a year. More importantly, it would have begun undoing decades of exclusionary zoning that encouraged McMansions and pushed starter homes toward extinction.

Our chamber enthusiastically endorsed the measure, the first business association in Massachusetts to do so. We did so because we saw an opportunity to create homes for young professionals near their jobs or where they grew up. Homes for teachers and police officers in the towns they serve. Homes where seniors could downsize without leaving their neighborhoods.

As Democrats across the country celebrated historic election victories as a mandate to tackle affordability, here in deep-blue Massachusetts voters rejected a tangible solution to one of the biggest drivers of our affordability crisis: housing costs.

Instead, the status quo prevailed, with Question 7 defeated in the closest outcome of the record-tying nine ballot questions, with 50.6 percent of voters saying no versus 49.4 percent voting yes.

Opposition came from different directions, driven by concerns about developer profits, changing “neighborhood character,” and the loss of local control. But with a margin this narrow, it helps to look at what tipped the balance and, more importantly, the silver lining we see in the results.

Because after all, the housing crisis that is crushing our economy and dampening our young adults’ spirits remains.

Those who voted ‘no’ didn’t know

Question 7 was designed to be as inoffensive as possible. While the MBTA Communities Act required cities and towns — some unaccustomed to large apartment buildings — to zone for multifamily housing, Question 7 took almost the opposite approach.

It would have opened the door to the very type of housing opponents to new growth often claim they want to preserve: single-family homes. Homes they, their parents, or grandparents owned. Homes now being bulldozed for McMansions.

Here is an often under-explained, but crucial, detail of the ballot question: Question 7 applied only to properties with access to public water and sewer — effectively excluding more than 78 percent of Massachusetts’s land area.

That should have reassured those in rural communities worried about infrastructure and development. Instead, the communities where the law wouldn’t have applied were among its strongest opponents.

• Municipalities with 90 percent to 100 percent sewer coverage supported Question 7 by more than 10 points.

• Municipalities with no sewer coverage, where the law would not have applied, rejected it by more than 20 points.

In other words, many voters appear to have opposed changes they feared would come to their backyards, even though it would have had little or no impact in their neighborhoods or town. The places where Question 7 could have done the most good were generally supportive, while the places where it would have had little or no effect on local development helped defeat it.

With a margin this small, that mattered.

Political muscle was MIA

Question 7 was conceived by Andrew Mikula, a long-time Wellesley housing advocate and chief housing economist at Pioneer Institute (he led this effort outside his day job).

Mikula is a soft-spoken, thoughtful, clear-headed thinker. He tirelessly championed this effort and was its ever-present face, voice, and heart. He had support from the pro-housing advocacy group Abundant Housing Massachusetts, the Citizens’ Housing & Planning Association, Eastern Bank’s Bob Rivers, and others.

Plus endorsements from the Globe, The New York Times, and even the Boston Herald.

We have nothing but respect, admiration, and gratitude for Mikula’s efforts. But the yes campaign lacked the political muscle and pizzazz we saw, for example, last week in New York City.

There, Mayor Zohran Mamdani championed a successful push for five ballot proposals aimed at streamlining government processes, cutting red tape, and accelerating development.

Yes, Gov. Maura Healey and Lt. Gov. Kim Driscoll endorsed the measure. But they were understandably focused on their own reelection.

Sen. Ed Markey was running too. He announced he was voting yes just days before the election, in a single social media post. Markey’s general election was a slam dunk; surely, he could have expended some political capital on this while crossing the state.

And where was Sen. Elizabeth Warren? Her career has been all about lifting up the middle class. She shepherded bipartisan legislation to expand housing production this year. She’s made housing affordability a major focus of her work.

Among the state’s congressional delegation, only Rep. Jake Auchincloss was an early champion of Question 7. And Rep. Bill Keating was the only other member of our delegation on the ballot committee’s list of official endorsers.

With a margin this small, that mattered.

Was the message just too wonky?

Here’s something else we’ve been wrestling with: Did voters actually understand what Question 7 would do?

Minimum lot sizes aren’t exactly intuitive. Explaining zoning requires striking a delicate balance. Too much technical detail loses voters. Too little leaves room for confusion and misinformation.

The campaign, operating on a limited budget, struggled with that balance. Consider its sole television ad. The 30-second spot offered just one explanation: “Yes on Question 7 will help us build the homes we need.”

True. But that was about it. And the dense, technical language voters encountered on their ballots probably didn’t help.

Explaining that “smaller lots mean smaller houses, which can mean cheaper houses” would have been a good start. Helping people understand that 5,000 square feet is about the size of an NBA basketball court would have helped, too.

So would positioning this as the alternative to “mansionization.” Nobody loves when a McMansion springs up in their neighborhood. It’s the one thing reflexive anti-development NIMBYs and YIMBYs (the acronym for pro-housing “yes in my backyard” advocates) both agree on.

With a margin this small, this mattered.

OK, so now what?

Despite our disappointment, we see a silver lining.

Voters in Brookline, Newton, Watertown, Arlington, Randolph, Amherst, Waltham, Malden, among others, backed this zoning change.

Those results should send a message to their city and town halls, including those like Brookline and Newton, which in some areas require single-family lots up to eight times the size Question 7 would have allowed. (That’s nearly a football field, without the end zones.)

Allowing 5,000-square-foot lots locally could help stem mansionization. It would create opportunities for smaller, more affordable homes in some of the state’s most expensive markets. Opportunities for folks to stay here. Opportunities for others to enjoy our special communities. Customers for our local businesses.

We call on city councils and select boards in our suburban communities — and in communities across Massachusetts that supported Question 7 — to act.

Finally, what about the state?

The narrow defeat of this small, simple reform may tempt some Beacon Hill lawmakers to retreat from top-down state zoning reforms. But retreating doesn’t address our soul-crushing housing crisis. Courage does.

Doing nothing is driving young adults out of state, leaving seniors stuck in homes they can’t maintain, and businesses struggling to attract and retain talent.

Last week, more than 1.25 million Massachusetts voters said yes to Question 7. They said yes to loosening exclusionary zoning rules, even at the expense of some local control. That’s hardly a ringing endorsement of the status quo.

We urge House and Senate lawmakers to approve two important proposals in the pending economic development bill: legislation to legalize duplexes statewide and so-called YIGBY legislation (“yes in God’s backyard”), which would make it easier for religious institutions to develop multifamily housing on their property.

Then we need to keep pushing. Keep moving forward. Keep building. We need to act as if future generations are depending on us, because they are.

With a crisis this large, this matters.

Greg Reibman is president and CEO of the Charles River Regional Chamber. Max Woolf is the chamber’s public policy and government affairs manager. Reibman was one of the 10 original signers of the petition to place Question 7 on the ballot.