Renee Gerrish, who is straight, tweeted a photo of the gay slur written on her rainbow-coloured tag.
“Someone at Delta Air Lines baggage handling took it upon themselves to write ‘sodomite’ on my luggage tag,” she said.
“Bigotry, hate speech and destruction of personal property while in Delta airline’s care.
“I want this shared and on behalf of the LGBTQ+ community — I will not go quietly.”
Ms Gerrish discovered the bag had been defaced after she landed at Atlanta’s Hartsfield-Jackson airport.
The Chicago woman told LGBTQ Nation the incident left her feeling “hurt and offended” and called it an act of “hate speech”.
“I wear LGBTQ+ support clothing and accessories regularly,” she said. “As a girl, I love rainbows, but as a symbol of love and support for the community that means everything to me.
“I don’t care if someone thinks I’m gay because of choices in rainbow accessories.”
Ms Gerrish wrote to Delta’s customer service team, saying: “As a hetero woman, I can only know my hurt, anger, and disappointment … PALE in comparison to what the LGBTQ+ community experiences on a daily basis.”
Delta said in a statement to LGBTQ Nation it “does not condone discrimination of a person or group for any reason”.
“As a global carrier with a diverse workforce, serving a diverse customer base, we are committed to treating all passengers equally,” the airline said.
Ms Gerrish said she was worried she wasn’t the only one who copped the slur.
“Delta is a brand that advertises their celebration of diversity but there are individuals employed by them who clearly don’t feel the same. And this was a result,” Ms Gerrish said, according to LGBTQ Nation.
“I’m sure I’m not alone. If this person did it to me, who knows what else they feel they have a right to do.”