It also is, according to City Planner David Taylor, an "Ellis Island of opportunity."
"Fifty thousand brand new people find us every year," Taylor says.
They can slip out just as fast.
Another 40,000 people leave Tucson each year.
There may have been some surprise but little shock when the city was told that one of the men suspected of hijacking and piloting American Airlines Flight 77 and crashing it into the Pentagon on September 11 once lived in Tucson.
A decade ago, Hani Saleh Hanjoor (also spelled Hanjour), who turned 29 on August 30, lived in Tucson for more than a year, including in a rooming house on North Fourth Avenue near East Speedway Boulevard. He also lived in Mesa and North Phoenix and attended a flight school in Scottsdale.
Messages for his Tucson landlord, a 60-year-old man who does not live at the rooming house, were not returned.
At 19, he was a slight figure--5-feet-6 and a mere 115 pounds, according to driver's license records--with brown eyes and black hair. He drove a Hyundai and by most accounts kept to himself. He was hardly remarkable. He tried hard to learn English and was enrolled in an intensive English as a Second Language course at the University of Arizona.
Taylor, among others who chart Tucson's profile, was not surprised there was a Tucson connection to the terrorist network of Osama bin Laden.
Part of that is because Taylor's memory clicked about another bin Laden follower, Wadih El-Hage, who was linked to terrorist bombings of U.S. embassies in Kenya and Tanzania in 1998. He was convicted of perjury and conspiracy to kill U.S. nationals. El-Hage, a former City janitor and driver for Van Tran, also was implicated in the 1990 murder of Sheik Rashad Khalifa, founder and spiritual leader of Masjid of Tucson.
Khalifa, whose name was made popular in Tucson by the success of his son, Sammy, on the baseball field at Sahuaro High School and with the Pittsburgh Pirates, was stabbed repeatedly at the mosque, 739 E. Sixth St.
The address is what made that stick with Taylor. He nearly rented the home, across the street from Tucson High School, in the 1950s.
Khalifa, once a science adviser to Libyan leader Moammar Gadhafi, received a doctorate in biochemistry from the University of California. His interpretation of the Koran sparked fury and death threats.
A 1992 raid in Colorado of what authorities say were terrorist cells known as FUQRA uncovered various plots, including maps and evidence of surveillance of Masjid. FUQRA, consisting mostly of American-born black Muslims, had a 100-acre compound at a central Colorado mountain pass near the town of Buena Vista.
More than an hour's drive west of Colorado Springs and two hours from Denver, Buena Vista is isolated, a place where outsiders of any kind stick out. Despite its many generations-old Hispanic population, it is an area where the locals grimace when Buena Vista is properly pronounced; they call it BE-U-NA VIHSTA.
While he was in Tucson, El-Hage, now 41, listed a rural Picture Rocks address that holds several mobile homes. He has been described as the leader of the Kenyan branch of Al Qaeda, a bin Laden terrorist group. He was a City janitor and a custodian for the Parks and Recreation department in 1988 and 1989. In September 1987, he was driving a Van Tran vehicle that collided with a motorcycle, crippling a young military veteran who was riding on the back of the bike.
El-Hage, according to testimony in the trial of those convicted of the 1993 World Trade Center bombing, had a role in directing a bin Laden pilot to purchase a jet at the boneyard near Davis-Monthan Air Force Base. The jet later crashed in Sudan.
Records show that El-Hage was ticketed in 1988 for failure to show proof of insurance, for which he paid a $34 fine.
HANJOOR AND A brother had ties in Tucson to Susan A. and Adnan Khalil, and the Khalils took Hanjoor in at their Hollywood, Fla. home for a month in 1996 when he arrived from Saudi Arabia.
"He was scrawny and he was painfully shy," Susan Khalil said in a telephone interview one week after her former guest flew an American Airlines jet into the Pentagon.
Hanjoor, she said, wanted to be a pilot, wanted to learn English and spent time at mosque. He then announced he was leaving for Oakland, for flight training. But he didn't stay in the East Bay, instead taking classes in Scottsdale.
Records show he, too, had minor traffic offenses, including failure to prove insurance and driving a car with an expired registration.
At about 1 p.m. on Friday, three days after Hanjoor's group orchestrated a takeover of four commercial jets, including the two that were crashed into the World Trade Center towers, Susan Khalil went to her home and turned on the television. Reports were releasing the names of the hijack suspects. She heard the name Hani Hanjoor.
"I just felt like I was kicked in the stomach," Khalil said. "It was the most horrifying thing you can imagine. It was upsetting enough what had happened on Tuesday, then lo and behold we learn one of them was a guest in our home.
"I was alone and screaming. I called my mom and she tried to calm me down, and then I called the FBI."
Agents talked to her and her husband for two hours that night, and the deluge of media ensued.
She thought about things they could give the FBI, pictures and phone records, which she provided.
"You can't imagine the horror," Khalil said. "We are more horrified than anyone."