For the first time since 1999, a Democrat will take the city's helm.
Attorney Jonathan Rothschild won 55 percent of the vote to Republican Rick Grinnell's 40 percent.
Green Party candidate Mary DeCamp trailed with about 5 percent.
Rothschild's win didn't come as a surprise to most political observers. In addition to a sizable Democratic voter advantage, Rothschild enjoyed a significant fundraising edge and had the entirety of the primary season to introduce himself to voters.
Grinnell, meanwhile, was a latecomer to the race, winning his spot in a successful - and rare - write-in campaign after three other mayoral hopefuls failed to qualify for the ballot by the traditional route.
To overcome the numbers disadvantage, Republicans needed Democrats to sit out the races. But they didn't.
As of late Tuesday afternoon, Democrats had a 39 percent turnout, compared with 43 percent for Republicans. With Tucson's Democratic edge in voter registration, however, that still meant 13,200 more Democrats voted than did Republicans.
Overall, turnout is expected to hover at 40 percent - just shy of Tucson's previous best, at 41 percent in 1999.
While outgoing Republican Mayor Bob Walkup rode a wave of dissatisfaction with city water policies to victory 12 years ago, Rothschild is similarly dealing with a frustrated electorate - a sentiment he said he clearly picked up in discussions with voters.
Rothschild's first task will be to help restore trust in city government, which has been sorely tested given wasteful Rio Nuevo spending, serious glitches in the 911 system, questionable development deals downtown and thefts in the parking program.
Although Rothschild was supported by each of the individual Democratic council members, he made a point on the stump of acknowledging voters' sentiment that the city is headed the wrong direction. Key among their complaints: a belief that the council has not been business-friendly and hasn't paid attention to bolstering economic development.
In a 180-day plan, Rothschild pledged to launch discussions with business interests and establish a small-business liaison in the mayor's office.
Speaking at a joyful Democratic celebration at the Lodge on the Desert midtown hotel, Rothschild said he's ready to begin 14-hour days, saying he'd make the mayor's office "an engine room" to accomplish his plan.
Rothschild said the challenges facing the city are stark, from aging infrastructure to deep poverty and an education system that needs improvement. "Tomorrow morning, the real work begins."
Tom Volgy, a Rothschild ally and former Democratic mayor, said that kind of talk on the campaign trail helped Rothschild woo voters.
"It's clear that Jonathan appealed clearly to what Tucsonans really want and need - a stronger sense of direction, a stronger economic focus, and an emphasis on an activist mayor who will pursue real viable options for us."
"Activist" may not be the first description some might apply to the soft-spoken Rothschild, who found himself defending his low-key style during the race. But Volgy said it fits. "I think we've had a mayor who was a symbol for Tucson but was not a very assertive public leader - and people were looking for someone who would be more assertive."
Volgy said Republicans needed to be far more organized out of the gate, which clearly didn't happen. "Rick Grinnell was going to have an incredibly uphill battle, particularly in a city that has far more registered Democrats."
Grinnell said he had anticipated a closer race, but complimented his volunteers for a strong effort. "There are no losers in this process," he said in an interview.
Had he not jumped into the race, he said, Tucson would have had a coronation and not an election.
Grinnell speculated his opponent was helped by the city's new vote-by-mail effort, which presumably made it easier for people to vote. And, he added, he thought the Democrats had an effective strategy of tying him to Rio Nuevo - he sits on the reconstituted state oversight board - saying voters were turned off by anything that had to do with the downtown redevelopment project.
Grinnell said he'll still continue to be engaged in Tucson politics anyway.
"The irony is, I'm still involved one way or the other - either as mayor or on the Rio Nuevo Board. So it's not like I'm going anywhere."
Grinnell surmised Rothschild is going to have his hands full with the Legislature, saying he's concerned that with a Democrat in the mayor's office, "the Legislature is going to be hard-pressed to do any big favors for Tucson." In particular, he said, he's concerned there may be moves afoot not only to possibly shut off the funding spigot for Rio Nuevo but to withhold state-shared revenues because of the ongoing investigation into whether project funds were misappropriated.
Republican Bruce Ash, who spearheaded an independent campaign to support the GOP slate, said while he endorsed Grinnell because he had a "unique background and talents for the job," he never thought Rothschild wouldn't be able to do the job.
Noting he's known Rothschild for 35 years, he added, "He is not just smart, but he's very civic-minded. I think this is going to be his life. And he is going to do everything possible to change the direction of City Hall."
Auto dealer Jim Click Jr., a major donor for the Republican Party, said while he supported Grinnell in the race, he too is optimistic about Rothschild's abilities. Praising his intelligence, Click also called Rothschild "a good guy" and said he looked forward to working with him. He said he had already set up a meeting.
City Clerk Roger Randolph estimated Tuesday night that 8,400 ballots remain to be counted, the bulk of those coming into the seven voting locations throughout the city. Since the signatures on those ballots still must be verified, Randolph said he hoped to have a final count completed Thursday, before the Veterans Day holiday. But those ballots are not enough to change the outcome in the mayor's race.
Reporters Rob O'Dell and Carmen Duarte contributed to this report. Contact reporter Rhonda Bodfield at email@example.com or 573-4243.