Hundreds of well-wishers and supporters lined Tucson's streets to cheer U.S. Rep. Gabrielle Giffords as she left University Medical Center and Arizona to begin a new phase of her recovery in Houston, Texas.

Giffords has made what her doctors call "remarkable" progress after being shot in the head during the Jan. 8 rampage in northwest Tucson.

PHOTO: Courtesy of Mark Kimble
U.S. Rep. Gabrielle Giffords (right, in her hospital bed) and husband Mark Kelly looked out over the Catalina Mountains from an outdoor deck at University Medical Center before departing for Houston, Texas, this morning.

Giffords' procession included her ambulance and a caravan of police vehicles and volunteer Veterans of Foreign Wars motorcyclists, with whom Giffords had ridden in 2009 to escort the remains of Civil War-era veterans from Tucson to Sierra Vista.

"She's one of our family," said one rider in the moments before departing. "We sent emails into her office saying we'd be honored to help her out."

The Congresswoman's caravan met with waving flags and applause along its route to Davis-Monthan Air Force Base.

Giffords' Medevac jet left the base's runway just after 10:20 a.m. and is expected to arrive in Houston, Texas, this afternoon.

Giffords' husband, astronaut and Navy officer Mark Kelly, who lives and trains at Houston's Johnson Space Center; her mother; UMC trauma surgeon Peter Rhee; a nurse and two longtime Giffords staffers traveled with her to Texas.

Upon arrival, she will be taken to the level-one trauma center at TIRR Memorial Hermann rehabilitation hospital, where she is expected to undergo a grueling physical therapy regimen in the coming weeks and months. The hospital specializes in patients recovering from catastrophic brain injuries, and has been ranked among the country's top five rehabilitation hospitals for the past 21 years.

Kelly said yesterday that he and Giffords' family chose the hospital because it would keep Giffords close to her husband and to her teenaged stepdaughters during this stage of her recovery. Nevertheless, he tweeted a promise this morning to be "back in Tucson ASAP!"

Watch video of her departure from UMC: