Authorities say Dava Denise Webster abandoned her 6-year-old son at Union Station on July 4 and walked away.
VIDEO: Mother arrested after child abandoned at Union Station, police say
Police had trouble identifying the boy, who did not communicate with investigators.
They say Webster returned to Union Station the next day, where she was recognized and taken into custody.
If convicted, Webster faces up to six years in prison, according to the Los Angeles County District Attorney's Office. Prosecutors are asking she be held on $100,000 bail.