Former Federal Reserve chair Janet Yellen on Tuesday formally became the first woman to serve as U.S. Treasury secretary in the department's 232-year history.

Yellen was sworn in by Vice-President Kamala Harris outside on the East Landing of the White House, becoming the nation's 78th Treasury secretary.

The ceremony, which observed physical distancing rules, came a day after the Senate approved her nomination by President Joe Biden by 84 votes to 15 votes.

She becomes the latest individual to break racial and gender barriers in the U.S. government. Others include Defense Secretary Lloyd Austin, the first African American to lead the Pentagon, and National Intelligence Director Avril Haines, who is the first woman to serve in the role.

Yellen, 74, also made history as the first female Federal Reserve chief from 2014 to 2018, will be tasked with helping the U.S. economy recover from the sharp downturn in growth and mass layoffs caused by the COVID-19 pandemic.

She is also expected to play a key role in gaining congressional approval of Biden's $1.9 trillion coronavirus relief package.

(With input from agencies)