For this Duran Duran classic many interpret the song as a love song to a girl, others believe it to be an ode to a glamorous Brazilian City but in reality it’s about America!
Specifically it’s about the band’s desire to “make it” in the U.S.
Rio is a metaphor for America, and the song expressed their desire to succeed there.
The lyrics clearly state, however, “from mountains in the North down to the Rio Grande,” which is the span of America. The Rio Grande river separates the US from Mexico.