"(I) expected to pass through customs without too much hassle as I was going on a tourist visa for 88 days, the max is 90, with my return ticket paid for," Hill wrote on Facebook.
"I was taken into an interview room and had every inch of my luggage searched.
"They understood that I have an American boyfriend and I spent about six hours in and out of the interrogation rooms.
"In the end they were convinced I wanted to immigrate illegally because my diary had notes like 'going away drinks' and 'last day at work', things I got in order before expecting to be away for three months."
Hill was not sent back to Australia immediately because there were no more flights and was forced to spend the night in a detention centre.
"A few more hours later, myself and a Japanese woman were handcuffed and transported to the detention centre, which was a federal prison," Hill said.
"I was frisked, made to undress in front of an officer and show that there was nothing in my hair or mouth, and asked to 'squat and cough' which was absolutely mortifying.
"Then I was provided a prison uniform and to add insult the officer gave me a size S bra and size L everything else."
Hill had to give authorities a list of her tattoos and was asked if any of them were gang related. Officers then handed her a blanket and a brown paper bag with a peanut butter and jelly sandwich inside, and hustled her into the women's prison.
To add insult to injury, Hill had plans to celebrate her birthday the next day.
Officers in the prison read Hill's file and told her she was unlucky and "you shoulda fell in love with a Canadian".
"The next morning it was my birthday. I was woken up by a flashlight and an officer who yelled 'Hill! You're getting released today'.
"I got changed (strip, squat routine) and was handcuffed again. I remained in handcuffs and was escorted throughout the airport. Then I was finally allowed to call home, and had to pay $620 for a flight to Sydney.
"I stared at the walls for another four hours, then my possessions were finally returned and I was escorted by customs security into the aeroplane for my next 11-hour flight."
Hill said the ordeal was surreal and took "a big chunk of money, heartache and tears".
Before the trip, Ms Hill resigned from her marketing job because she was away for such a long period. Her former boss Mini Sarkissian told the Herald Sun that was common practice.
"I do that for all my staff who want to take holidays for an extended time. If you take more than six or seven weeks you need to resign. I don't think that's unreasonable for companies," she said.
Ms Sarkissian said she was shattered when she saw the Facebook post detailing the horror ordeal, and had plans to hire Hill again when she returned if there was an opening in the company.
Her former employer told the Herald Sun she was concerned authorities were drawn to Hill because she had recently quit her job, but said it was not uncommon for young people to travel for long periods.
News.com.au has contacted US Customs and Border Protection for comment.
