Fans queued en masse Tuesday to pay their respects to legendary US singer and "Queen of Soul" Aretha Franklin, whose body lay in a golden casket dressed in a ruffled red dress and matching heels in Detroit.

The 76-year-old icon, beloved by millions around the world, died of cancer on August 16, bringing down the curtain on a spectacular six-decade career that made her one of America's most celebrated artists.

Thousands of people are expected to bid her farewell at the Charles H. Wright Museum for African American History on Tuesday and Wednesday, followed by an afternoon viewing at her father's New Bethel Baptist Church on Thursday, and a star-studded funeral on Friday.

White-gloved, sharp-suited pallbearers escorted her casket into the museum on Tuesday, ahead of the two days of 9 am to 9 pm viewing, where she lay in state surrounded by enormous clouds of pink, white and purple roses.

Considered royalty in her Michigan hometown of Detroit, people reportedly camped out through the night to pay their respects with some travelling from far and wide, at times breaking into song or wearing Aretha T-shirts.

They queued down the street and around the block before the museum opened with a steady flow trickling inside by mid-morning, an AFP reporter said.

People stood subdued on the marble floor to gaze at the roped-off musical icon, resplendent in her finery and ankles crossed in red pumps.

The gospel, soul and R&B star legend influenced generations of singers with unforgettable hits including "Respect" (1967), "Natural Woman" (1968) and "I Say a Little Prayer" (1968).

"She's the Queen. She's an icon, a legend. It's just an honor to be able to be here to pay tribute to her," one man told Detroit's Local 4 News.

'An honor'

Franklin won 18 Grammy awards and provided a soundtrack to the civil rights movement, singing for free to raise money for the cause and uplifting activists with her phenomenal voice and upbeat anthems.

Her signature song, "Respect" – recorded as a feminist anthem – became a rallying cry as African Americans rose up nationwide in the 1960s to fight peacefully for racial equality.

"Her music changed the lives of many and it's an honor to be here," said one mourner who journeyed from Toledo, Ohio. "She touched so many people and it's just a blessing," he told Local 4 News.

Franklin follows civil rights icon Rosa Parks, who also lay in state at the same Detroit museum after she died in 2005.

A free tribute concert honoring Franklin's life will be held on Thursday evening, before her funeral at the Greater Grace Temple on Friday, where Stevie Wonder and Jennifer Hudson are among stars expected to perform.

Former US president Bill Clinton, Smokey Robinson and Jesse Jackson, the civil rights leader, are among those expected to attend the invitation-only service, which will be broadcast to the public from a large screen outside.

In her 1985 hit "Freeway of Love," Franklin sang about cruising in a pink Cadillac. More than 100 pink models of the iconic US automobile are expected to file in outside the church on the day of her funeral.

The car company was founded in 1902 in Detroit, for decades the home of the US motor industry.

She performed at the inaugurations of presidents Bill Clinton and Barack Obama, singing "My Country 'Tis of Thee" at the investiture of the country's first African-American head of state.

In 1987, she became the first woman ever inducted into the Rock and Roll Hall of Fame. In 2010, Rolling Stone magazine put her at the top of its list of the 100 greatest singers of all time, male or female.

She married and divorced twice, and had four sons, including two by the time she was 15 years old. Franklin died surrounded by family and loved ones, from advanced pancreatic cancer.

(Cover: The body of Aretha Franklin lies in repose at the Charles H. Wright Museum of African-American History on August 28, 2018 in Detroit, Michigan. /VCG Photo)