Robert Houston: witness to injustice and social change – in pictures

The American photographer Robert Houston, who memorably documented the civil rights movement, poverty and homelessness in the United States, has died aged 86. Born in East Baltimore in 1935, he was inspired by his friend and fellow photographer Gordon Parks to start work for the Black Star agency and then at Life magazine, for which he notably covered the Poor People's Campaign of 1968. Here is a selection of his photographs mainly from those years