"Consider this, there are 683,700 passenger vehicles and trucks registered in Salt Lake County," Hansen wrote Friday. "In Davis and Weber counties, we have a combined number of 342,468. . . . It seems your air pollution problems are mostly within your own borders."

Hansen's anger comes in response to comments Anderson made this week in his State of the City speech, which the mayor used as a soapbox against the proposed Legacy Highway that would connect southern Davis County with Salt Lake City.

"We want our friends from the north to come to Salt Lake City," Anderson said during his hourlong speech. "We just don't want them to increase our city's traffic, further foul our air, undermine the quality of our lives and make us sick, simply because of the choices they make about where they live and how they get around."

Hansen, who took office Jan. 3, called Anderson's remarks "completely absurd."

"This is hardly what I would call throwing out the welcome mat," Hansen wrote.

Anderson, reached late Friday afternoon, stopped short of issuing a mea culpa for his comments about what he sees as a threat to his city. Though he invited "our friends up north" to come to Salt Lake City, Anderson said the problems are not limited to Davis County and the proposed Legacy Highway.

"When our citizens are told 40 days of the year that they can't exercise outside or that the young and the elderly and those with cardiac and respiratory health concerns should not leave their homes, we have got to have people fighting to fix the problem," he said.

Laying down more asphalt only encourages driving, he said.

Officials in Davis County felt similarly stung when Anderson joined a lawsuit that suspended construction on Legacy Highway in 2002. They later persuaded legislators to withhold $2.4 million earmarked to help Salt Lake City recoup costs for hosting the 2002 Winter Olympics.

Anderson got his money after he agreed not to join in any further legal battles regarding Legacy.

"I have not broken my word to stay out of the litigation," he said. "But I have never said that I will not be an advocate of finding an alternate route, rather than the one proposed and putting other means of mass transportation first."

Hansen's letter notes that Davis County wants more transit - light rail, commuter rail and improved bus routes - but stresses that residents need Legacy Highway, too.

In an interview, Hansen said Anderson should remember that I-15 runs in both directions.

"Your city is not an island surrounded by a moat with you at the drawbridge," Hansen wrote. "Your chamber welcomes us to shop and spend money at your places of business just as we welcome all residents to do the same here."

The letter was written on Davis County letterhead but carried only Hansen's signature. The other commissioners, Carol Page and Dannie McConkie, are out of town.

"They have no idea I've done this," Hansen said. "I don't want to speak for them but I think most people would find his comments insulting."

lorib@sltrib.com