Nancy Pelosi, who scripted history by becoming the first female speaker of the US House of Representatives, was re-elected to the post, easily trouncing her Republican rival.

Pelosi, a Democrat from California, defeated Republican John Boehner by 255 votes to 174 on the first day of the 111th Congress.

With this Pelosi would now lead the ruling Democratic Party in the House of Representatives which has 20 more Democrats than the previous Congress.

"Thank you to my caucus for granting me the historic opportunity of breaking the marble ceiling and to serve, once again, as the first woman Speaker of the House," she said, soon after her re-election as she pledged to govern from the middle.

Referring the economic recession, she pressed that the new caucus held the responsibility to work together at a time of "profound challenge".

"Without reservation, let us stand together -- not just today, but in the days ahead -- to live up to that resolve. Few Congresses and few Presidents in history have been given the responsibility and the privilege of serving the nation in a time of such profound challenge," Pelosi said.

Welcoming new members, Pelosi asked her colleagues in the House of Representatives -- both Republicans and Democrats -- to shed their differences in order to work together for the American people.

"We will look forward, not backward; we will join hands, not point fingers; we will rise to the challenge, recognising that our love of country is stronger than any issue which may divide us," she said.