MEXICO CITY (Reuters) - Mexico handed Sandra Avila, Mexico's highest-profile woman drug smuggler known as the "Queen of the Pacific," over to United States authorities on Thursday to face trafficking charges north of the border.

Avila, who was arrested in Mexico in 2007, allegedly helped build up the Sinaloa cartel in the 1990s with the gang's leader Joaquin "Shorty" Guzman. She won her nickname for pioneering smuggling routes up Mexico's Pacific Coast into California.

The Mexican federal attorney-general's office said she would face cocaine possession and distribution charges in Florida.

Avila, who was given into the custody of U.S. officials in Toluca, was nabbed on organized crime and money-laundering charges in Mexico and had fought extradition by claiming she would be tried for the same crimes twice.

Avila is the niece of Miguel Angel Felix Gallardo, known as the godfather of the Mexican drug trade.

The country's drug war has claimed more than 55,000 lives since President Felipe Calderon sent the army out to battle drug gangs in late 2006.

(Reporting by Anahi Rama; writing by Krista Hughes; editing by Todd Eastham)