WASHINGTON DC: Barack Obama rode into the US capital on a vintage train on Saturday, starting three days of celebrations before his inauguration as the 44th US president.

But the president-elect warned Americans of the great challenges the country faces, too, because he takes office amid the deepest economic crisis in generations and the wars in Iraq and Afghanistan.

Obama evoked imagery of Abraham Lincoln - as he had done throughout his campaign - when he took the shortened version of the train journey that Lincoln had taken before assuming office in 1861.