White House hopefuls and groups supporting them spent a total of $US2.17 billion ($A3.01 billion) during the election campaign that Republican Donald Trump finally won, according to a analysis.
The project - conducted by the Center for Public Integrity and analysing figures compiled by the Federal Election Commission, tax authorities and other reports - concluded that Trump and groups supporting him spent $US409 million, a little more than half of the $US759 million his Democratic rival Hillary Clinton spent.
That means that each of the 62.979 million votes Trump secured cost him $US6.50, while each of Clinton's 65.845 million votes cost her $US11.50.
Despite losing the popular vote by more than 2.8 million votes to Clinton, Trump won because he garnered more than the required 270 electoral votes needed to become president.
Trump received 306 electoral votes - and ultimately 304 of those electors voted for him - while Clinton received 232, of which 227 voted for her.
According to the study, Trump spent $US66.1 million of his own money to help finance his campaign - a figure that is just 11 per cent of the $US600 million the real estate magnate had said in 2011 that he was ready to spend if he decided to run for the White House.
Of the other White House hopefuls in the 2016 campaign, those who spent the most were Senator Bernie Sanders, who laid out $232 million vying with Clinton for the Democratic presidential nomination, and Senator Ted Cruz, who spent $US161 million trying to obtain the Republican nomination.
Behind them come two more Republicans: former Florida Goveror Jeb Bush, spending $US154 million, and Senator Marco Rubio, spending $US111 million.
The authors of the study say that only Sanders did not receive financing from political action committees, or PACs, while Clinton received $US205 million from such groups, Trump $US89.4 million, Cruz $US69.3 million, Bush $US122 million and Rubio $US76.5 million.
