It was a rare moment when Republicans and Democrats united -- on a U.S.-Mexico border measure, no less.

But this bill was not just any bill. 

It was the last piece of legislation offered by Arizona Rep. Gabrielle Giffords, who made a painstaking effort to walk into the chambers of the House of Representatives on Wednesday to cast her last vote and to submit her resignation, more than a year after she was gravely wounded by a would-be assassin.

Giffords' bill would impose tougher penalties on smugglers who use small, low-flying aircraft to avoid radar detection and bring drugs across the Mexican border.

The vote was 408-0.

The Democratic congresswoman introduced the legislation along with fellow Arizonan Jeff Flake, a Republican. 

It's similar to a version that easily passed the House in 2010 but did not make it through the Senate. Her office said the current law allows defendants who use ultra-light, single-seat planes to get a lesser penalty than those who use cars or other types of planes to smuggle drugs.

“Congresswoman Giffords is committed to taking this crucial step that would help secure the border against drug smugglers,” said Pia Carusone, chief of staff to Giffords, in a statement on the congresswoman's website. “That’s why she decided this would be the last bill she introduces before she steps down.”

The measure would establish the same penalties for trafficking, whether by plane, automobile or ultralight: up to 20 years in prison and a $250,000 fine.

The website says that Sen. Tom Udall of New Mexico "is working to get quick approval of the bill in the Senate so that it can be sent to the White House for the president’s signature."

Tears flowed in the chambers Wednesday as Giffords' colleagues said goodbye.

Giffords had come to the well of the chamber to resign, a formality since she'd signaled her intention earlier, as she recovers from a gunshot wound to the head during a shooting rampage in her home district in Arizona. 

It was one of the longer House goodbyes in recent times, as Democrats and Republicans lined up to see her off. A prolonged standing ovation followed a fusion of tributes and tears as colleagues praised her dignity and perseverance.

Surrounded by friends and colleagues and holding Rep. Jeff Flake's hand, Giffords heard her close friend, Rep. Debbie Wasserman Schultz, read her resignation letter to the chamber. In it, Giffords said she had "more work to do on my recovery before I can again serve in elected office."

Last January, a gunman opened fire at Giffords' "Congress on Your Corner" event in Tucson, killing six people and wounding 13, including Giffords who suffered the gunshot wound.

"I don't remember much from that terrible day, but I have never forgotten my constituents, my colleagues or the millions of Americans with whom I share great hopes for this nation," Giffords said in the letter to House Speaker John Boehner, R-Ohio.

After reading it, an emotional Wasserman Schultz helped Giffords slowly make her way to the podium where she handed the letter to a teary-eyed Boehner.

House Democratic Leader Nancy Pelosi, D-Calif., said Giffords had become "an inspiring symbol of determination and courage to millions of Americans ... Her message of bipartisanship and civility is one that all in Washington and in the nation should emulate."

House Majority Leader Eric Cantor, R-Va., said Giffords' "strength against all odds serves and will continue to serve as a daily inspiration to all of us."

Giffords submitted resignation letters to both Boehner and Arizona Gov. Jan Brewer, but it isn't effective until the end of the day.

It falls to Brewer to set a date for a special primary and general election to fill the Arizona seat. That will probably happen in the spring or early summer. In November, voters will choose someone for the full two-year term.

Whoops, cheers and sustained standing ovations greeted Giffords' arrival in the chamber. Holding Wasserman Shultz' arm, the congresswoman moved down the center aisle, receiving kisses and hugs from her colleagues.

Her mother, Gloria, and husband, retired Navy Capt. Mark Kelly, watched from the gallery. Giffords had announced on Sunday in a Web video that she would resign her seat.

"She realized she was not going to run for re-election and this point the right thing to do was for her to step down," Kelly said after the emotional event on the House floor. "But I'm more optimistic than anybody else about her future. She just needs some more time, whether it's a year or two years or three years, I'm very confident she's going to have a long and effective career as a public servant."

Asked about her daughter's future, Gloria Giffords said, "I kind of think she's transcended Congress. I don't know where she's going to end up."

"She's remembered every boy she's ever kissed, every song she's ever sang, every bill she's ever passed," she said. "So upward and onward."

This story contains material from The Associated Press.

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