PHOENIX, Ariz. (AP) _ A convention boycott against Arizona to protest Gov. Evan Mecham's cancellation of a holiday honoring the Rev. Martin Luther King Jr. apparently isn't changing his mind, but it's having a big impact on others.

''I don't know if Mecham was right or wrong. All I know is this thing is taking money out of a lot of pockets, including mine,'' taxi driver Joe Morales said last week as he waited for business at a downtown cab stand. ''It always gets slow in the summertime, but it never dies. This year it's just dead.''

Thirty groups have canceled conventions in Phoenix over the issue, including education, health, media and religious organizations, the city's convention and visitors bureau says. Entertainers such as the Doobie Brothers and Stevie Wonder also have participated in the boycott.

The bureau estimated that the boycott cost $8.1 million in lost convention business through last week, at $609 per convention-goer, and projected that the year's loss could pass $18 million.

''It's not just one hotel that's being hurt,'' said Steve Sokal, general manager of the Hyatt Regency Hotel. ''It's local restaurants, dry cleaners, airlines, the gift shop in the lobby. Everybody is feeling the impact.''

In 1986, conventioneers spent $297 million in the Phoenix area, the bureau estimated. The $8.1 million loss for this year is approximately 2.7 percent of that total, with seven months of the year remaining.

But the actual impact on the local economy is greater, officials said, because the loss estimate doesn't count business activity supported indirectly by conventions, and because it counts only groups that cancel conventions, not those that decide to go elsewhere.

''We can't possibly determine the actual loss involved, because we don't know how many groups have decided not to even consider us,'' said Phoenix Mayor Terry Goddard.

Conventions and meetings also have been canceled in Tucson, Mesa, Scottsdale, Tempe and Sedona.

On Monday, Mecham spokesman Ron Bellus said the governor doesn't dispute the convention bureau's loss estimates but does question the significance on Arizona's overall convention and tourism industry.

''He did what he had to do legally as he saw it,'' Bellus said. ''There's nothing more he can do. He's left it with the Legislature, where it belongs.''

The boycott was spurred by Mecham's decision, days after he took office in January, to rescind an executive order issued last year by his Democratic predecessor, Bruce Babbitt, that created a holiday for state executive-branch workers in honor of the slain civil rights leader.

Mecham, a Republican, argued that Babbitt's action was illegal because only the Legislature could declare a state holiday. Mecham denied he had any racist motive, as some critics charge.

During the legislative session that ended in May, the House approved a King holiday bill, but it was defeated in committee in the Senate. Both houses are controlled by Republicans.

''I don't believe Governor Mecham and a few senators who are against the bill speak for the majority of Arizonans,'' said the Rev. Warren H. Stewart, a Baptist minister in Phoenix and a boycott supporter. ''I think the majority are justice-loving, peace-seeking people who see the significance of the changes Martin Luther King Jr. brought about in our nation.''

Mecham has contended that some groups will come to Arizona because of his stand, and said Saturday that those who have canceled performances and conventions are ''black entertainers (and) a few people from the liberal fringe.''

Wonder, who is black, announced he would boycott the state, and a May reunion concert of the rock band Doobie Brothers was moved elsewhere because of the issue. Other acts, such as the Irish rock group U2 and folk singers Peter, Paul and Mary, criticized Mecham but performed scheduled concerts.

Officials said they hadn't heard of any jobs lost because of the boycott, but they didn't rule out that prospect.

''If business drops by 5 percent, the payroll and other expenses are going to have to be cut by 5 percent,'' said Robert A. Rauch, president of the Valley Innkeeper Association and manager of a hotel in Mesa.

The competitive nature of the convention industry makes the losses frustrating to those who work to persuade groups to pick Arizona for their meetings.

''There's much more competition for the convention dollar than every before,'' said Lloyd Axelrod, the convention bureau's vice president for public relations. ''It can take years to sell a group on having a convention in your area.''