DENVER -- About a dozen people lined up outside Argonaut Wine & Liquor in Denver before it opened for business Sunday, the first day liquor stores could sell alcohol on Sundays under a new state law.

"There's a lot of people celebrating what they see as a historic occasion in Colorado," said co-owner Ron Vaughn. "They're getting mimosa mixings and everything else."

Not every liquor store was open Sunday, though.

In Boulder, Gunbarrel Liquor owner Petur Petursson said he had no interest in giving up his one day off of the week -- or in taking it away from his employees.

"You need a day to unwind and catch up with your families, and every other day is too hectic," he said. "Having that day means a lot to everybody, so we just felt no need to change that."

Colorado is the 35th state to allow Sunday alcohol sales at retail stores and the 13th state to pass such a law since 2002, according to the Distilled Spirits Council of the United States, the trade group that has lobbied for such laws across the country.

Liquor store owners had opposed attempts to repeal the Colorado blue law three years ago but changed their minds after supermarkets pushed for the right to sell full-strength beer and wine.

Supermarkets say they should be now be allowed to sell beer and wine because few people will continue to by the 3.2 percent beer they're allowed to sell.

Petursson said about 90 percent of his customers support his decision to have a day off, despite the new law.

Thomas Valdez, proprietor of the Niwot Liquor Store, also was keeping doors closed Sunday. He figured he would have to spend more money keeping the lights on and paying someone to staff the counter in exchange for what he expected would be meager sales.

"In my market, when I tried to find someone who would work on Sundays, they weren't rushing to the store, that's for sure," he said.

Vaughn said Sunday morning that it was too early to say if staying open for the day would be worth it, but he said the store was "pretty busy" in the first few minutes of opening.

"We're just glad to be open for the customers who wanted us to be open Sundays," he said.