The United States marks the 250th anniversary of its independence on Saturday amid a historic heat wave that has forced the suspension or rescheduling of events in several cities across the country. The semiquincentennial commemoration, recalling the adoption of the Declaration of Independence in Philadelphia in 1776, will have its centerpiece on the National Mall in Washington, with a speech by President Donald Trump and the largest fireworks display in history.

Cities open cooling centres, extended pool hours and urged residents to conserve electricity

A punishing heat wave threatened America's July 4th celebrations, World Cup matches and power grids as near-record temperatures scorched the eastern United States on Friday.