She was greeted by friends and family at a reception at the Gurnee American Legion Post.
The 20-year-old is home from a one-year deployment, which included eight months in Iraq working as a facilities support specialist.
"There is no word really to describe the happiness when you know you're back in America," Erwin said. "It's just really awesome."
"She's always been a good kid, always very smart. We hope she'll make a difference in the world someday," said John Erwin, the soldier's father.
Megan Erwin received the Army's commendation medal for meritorious service during her time in Iraq.
