Months before Tuesday's election, John McCain and Barack Obama were secretly planning for a job only one of them will face, transitioning their political campaigns into a governing machine.
The new president will have a transition of just 77 days from his election to his inauguration to slow the ship of state, replace thousands of government officials and chart a new course.
Since the first transition, in 1797, from president George Washington to John Adams, the peaceful handover of power has become ever more choreographed with each successive administration, especially since World War II.
But the 2009 cycle, from President George W Bush to his successor will be more fraught than usual, with the United States mired in a financial crisis and with more than 150,000 soliders in combat abroad.
"You have to go back to 1933 to find a transition as equally challenging as this one," said Darrell West, director of Governance Studies at the Brookings Institution, citing the transfer of power to Franklin D Roosevelt during a banking crisis.
"We have a bad economy, we have two wars, basically there is no money for the new president to address the major problems."
Unlike nations which have a permanent civil service, many top positions in the US government are political appointments, meaning that whole ranks of staff are flushed out by an incoming president.
Tales are legion of aides showing up to work at the White House after the inauguration to find computers stripped of hard discs, offices with no files and no idea how to do their jobs.