In Charlotte, which has a large convention center, more than 20 conventions have either canceled or are no longer considering holding their event in the state, resulting in a loss so far of around $2.5 million, according to the Charlotte Regional Visitors Authority.

The Westin Charlotte, a Starwood property next to the convention center, is also seeing a dip. “Over 55 percent of our business comes from groups, and 11 groups have pulled us from consideration” because of the law, said David Montgomery, the property’s director of sales and marketing at the hotel, which has hung a large banner that says “Always Welcome” on its exterior, part of a campaign by the local tourism authority.

Dr. Barbara Risman, a sociology professor at the University of Illinois at Chicago and the former president of the Southern Sociological Society, a Virginia-based group dedicated to sociological research, recently canceled the group’s conference of 1,200 attendees at the Westin, scheduled for 2019, because of the law. “We don’t want to spend our money in a state that discriminates against the L.G.B.T. community,” she said, “and since our members often bring their families along to the conferences and stay in the destination for a few days after for fun, we’re talking about tourist dollars from airfare, hotel rooms and meals not going to Charlotte.”

Gov. Pat McCrory of North Carolina, though, says a Charlotte ordinance set in motion the law he signed last month. Mr. McCrory, whose office did not respond to requests for comment, said on “Meet the Press” recently that the law was an attempt to counter a city ordinance banning discrimination against gays, lesbians, bisexual and transgender people.

Regardless of the locus of the political tensions, the cancellations are being reported statewide. Marriott International, with 134 properties across its portfolio of brands in North Carolina, and Starwood Hotels & Resorts Worldwide, with 20, are also seeing canceled reservations. In an email, Ken Siegel, Starwood’s chief administrative officer and general counsel, said, “Anecdotally, we know that some guests have canceled bookings at our North Carolina properties after the law passed to take their business outside of the state.”