Representative Gabrielle Giffords was due to meet on Monday with some of those present when she was shot in the head last year, part of a final flurry of duties before she resigns from the U.S. Congress this week.
Giffords was struck by a bullet on January 8, 2011, when a gunman opened fire at a congressional outreach meeting outside a Tucson grocery store, killing six people and wounding her and 12 others.
In an announcement on Sunday, the Arizona Democrat said she would resign from office this week to focus on her recovery from the head injury that left her with faltering speech and some restricted movement.
"I have more work to do on my recovery, so to do what is best for Arizona I will step down this week," Giffords said, posting the announcement on social media such as Twitter, Facebook and YouTube.
"I'm getting better. Every day my spirit is high. I will return and we will work together for Arizona and this great country. Thank you very much," she added.
In her final act in Tucson as a member of Congress, she planned to meet on Monday with some of the people who were present at the shooting, and then visit a food bank, her office said.
Giffords was seen as a rising political star, one of the Democrats to survive the Republican sweep of swing districts in the November 2010 elections.
Giffords, a Democrat who gained a reputation as a centrist, also plans to attend President Barack Obama's State of the Union address to Congress on Tuesday.
Her office said she would submit her letter of resignation this week to House Speaker John Boehner and Arizona Governor Jan Brewer. Arizona law requires Brewer to call a special election to fill Giffords' seat.
Since the shooting, she has received intensive therapy at a hospital in Houston, Texas, and she has been assisted by her husband, retired astronaut Mark Kelly.
Jared Loughner, a 23-year-old college dropout, was charged with attempting to assassinate Giffords and other crimes stemming from the incident. He pleaded not guilty and was found mentally unfit to stand trial.
After she announced her retirement, she received tributes from President Barack Obama and both sides of the aisle in the U.S. Congress.
"Cindy and I join our fellow Arizonans in thanking Gabby Giffords for her service in the U.S. Congress and to her constituents in Southern Arizona," Senator John McCain, an Arizona Republican who ran against Obama for president in 2008, said in a statement Monday.
"Gabby's courage in the face of tragedy inspired our nation and made all Arizonans proud. We wish Gabby and her family all the best in the future."