The Prime Minister will meet with Barack Obama today to discuss trade liberalisation, development and Syria during his three-day visit to America.
The two leaders will be joined in the Oval Office by US secretary of state John Kerry, Mr Cameron's national security adviser Kim Darroch, and opposite number Tom Donilon.
David Cameron will urge a peace conference on Syria by the end of the month, believing that efforts to end the 27 month conflict have gained some momentum after his trip to Sochi for talks with President Vladimir Putin last week, and Mr Kerry's visit to Moscow.
One of the main obstacles to easing the situation has been Russian support for Bashar Assad's regime.
More top news
Union leaders and officials from a range of campaign groups will address demonstrators as Conservative party conference gets under way.
Teachers union says workload, pay and low morale drive educators away from the profession.
Prime minister says he will 'beef up' special force and boost the use of drones in fight against terror group.