A record number of District lawmakers flew to Las Vegas at taxpayer expense for the annual conference hosted by the International Council of Shopping Centers. (Larry MacDougal/Associated Press)

Nine of the 13 D.C. Council members, along with Mayor Muriel E. Bowser and city staff, were returning Tuesday from three days of socializing and meeting in Las Vegas with real estate developers and major retailers.

A record number of city lawmakers flew to Vegas, most, if not all, at taxpayer expense, for the annual conference hosted by the International Council of Shopping Centers, which bills itself as the world’s largest gathering of retail companies.

Bowser (D) and the council members threw a party — funded in part with tax dollars — at the plush Foxtail Nightclub on Sunday night, where Bowser told retailers that the District has options and wants more.

The message was similar on Monday night at an invitation-only gathering of business leaders and developers at the rustic La Cave restaurant at the Wynn Las Vegas hotel, where Bowser made a pitch for more grocers, especially east of the Anacostia River.

Awash in a building boom and flush with millions of square feet of new retail space downtown, District leaders have not let up in their courting of national retail chains that began when the city was shunned by developers during the deadly drug wars that plagued it in the 1980s and 1990s.

“It’s great. D.C. has changed, and we can make a different pitch than we could make years ago,” said D.C. Council member Jack Evans (D-Ward 2). “It used to be that we had to tell them about the vision of what D.C. could become. Now, everybody wants to come open a store in the District.”

But that turnaround — coupled with the city’s staggering income disparity — is fueling questions about whether the mayor and a supermajority of the council should have traveled to Las Vegas to pitch retail executives on coming to the District.

“It doesn’t make any sense that elected officials need to go pitch prospective tenants,” said Greg LeRoy, executive director of Good Jobs First, a watchdog group that tracks government subsidies for businesses. “The decision of a national retailer is a cold, hard calculation about whether you can justify enough sales to afford the rent; that’s it, it’s not about what politicians say.”

Monica Kamen, co-director of the DC Fair Budget Coalition, echoed that concern.

“There’s been a lot of development in D.C. that has led to massive gentrification and a rise in the cost of living, and we need to be looking at how we continue development without further displacing people,” Kamen said, noting that the lawmakers’ excursion comes only a week before the D.C. Council is scheduled to vote on a $13.8 billion city budget.

“A week before the budget vote, I would hope that that is where most of their focus was — on how to maximize spending for those in need . . . not in Las Vegas talking about giving away too many tax dollars to retailers,” Kamen said.

Council members and representatives for the mayor defended the trip Tuesday in a series of phone interviews.

Brian Kenner, the deputy mayor for planning and economic development, who has attended the conference almost every year for a decade, said that the District has benefited from a consistent presence at the event.

“The fruits are evident in the amount of retail we have gotten in D.C.,” Kenner said. “Retailers take a long time to make decisions, not weeks or months, but years.

“You can talk to one retailer and they’re downsizing and not interested, and three years later, it’s completely reversed. We know we’ve got to be here talking to retailers when they are up or down.”

By several estimates, the District’s contingent of taxpayer-funded lawmakers and staffers was the largest of any city. The city had a large walk-in display area at the conference, hosted parties and receptions and was represented by 24 lawmakers and government staffers, according to a document circulated among participants.

Additional staffers and executives also traveled under the auspices of the public-private Washington DC Economic Partnership, which is partly funded by taxpayer money. The partnership paid for all attendees’ registration, the District’s display area, the welcome reception and other events.

Few of the nation’s top 20 cities sent representatives, according to lists of attendees on the ICSC website.

The full accounting of how much the trip cost taxpayers was not available Tuesday. An attorney for the D.C. Council said the request for that information would be treated under ­open-records guidelines, giving the council 15 days to respond. The mayor’s office also did not provide a breakdown and declined to identify where the mayor and her top aides stayed.

Evans, who has been attending the conference since the administration of Anthony Williams, said that the District would be foolish not to go and that the travel costs are a sound investment.

“Frankly, if we weren’t here, we wouldn’t be doing our jobs,” Evans said.

He noted the Saturday announcement that popular grocery chain Wegmans plans to open a store along Wisconsin Avenue in 2022.

“We’ve been talking to them here for five years — and now we’ve got them,” Evans said.

Evans said this year he and other council members met with German grocer Lidl about sites in the District and discussed with grocers Giant and Safeway how to encourage them to expand in the city’s poorest areas east of the Anacostia River.

But an itinerary for the group also showed several meetings with D.C. developers, including the JBG Cos. and Hines, and with others seeking tax incentives for development around Union Market.

Along with Evans, eight other council members were on the trip: Brandon T. Todd (D-Ward 4); Kenyan R. McDuffie (D-Ward 5); Vincent C. Gray (D-Ward 7); Trayon White Sr. (D-Ward 8); Robert C. White Jr. (D-At Large); Anita Bonds (D-At Large); David Grosso (I-At Large); and Chairman Phil Mendelson (D).

The nine amount to a supermajority of the council, but Mendelson said he was never in a meeting with more than four or five at a time and the council members never held an official meeting that would violate open-meeting laws.

“It’s no different than when the council members are in Washington, D.C.,” Mendelson said. “We are not required to file an open meeting notice when we go to a party in D.C.; we are not required to file one when we go to a party here.”

Mendelson said he was sensitive to the perception that council members were using a lot of public tax dollars for the trip and was concerned about whether lawmakers were being “careful” to keep expenses to a minimum.

Council members each have an annual budget of roughly $19,000 for office supplies and nonpersonnel expenses. The money can be used for travel for both lawmakers and their staffs, and with the council session nearing an end, some council members have been known to use the majority of what is left each year on the Vegas trip.

Evans, McDuffie, Grosso, Todd, and Robert C. White Jr. brought along staff, according to the list of attendees.

McDuffie, who chairs the committee with oversight of business affairs, said it was important to have his top two staffers to organize meetings, arrange follow-ups, and visit booths of retailers when he could not.