Burning flags, busty blondes and bison skulls: 48 photographs that capture America at 250

From the gold rush to civil rights, the moon landing to 9/11, the US has always understood, mythologised and sold itself through the power of the still imageThe United States was founded in 1776, but did not begin to see itself until the autumn of 1839, when daguerreotypes, the first form of photograph, reached American cities. You could argue the US began again on the morning it could look at its own face.At first photography seemed to answer the democratic promise of 1776. A portrait was no longer reserved for the rich; almost anyone could now leave a trace of their existence. The gold rush became one of the first great American dramas to find the camera: ordinary diggers squinting into the lens, looking beyond it for gold. A more emblematic American scene can scarcely be imagined: what