Julie Mehretu Until 8 August at the Whitney Museum of American Art, 99 Gansevoort Street, Manhattan Julie Mehretu’s massive mid-career survey—which has travelled from the Los Angeles County Museum of Art—includes more than 70 paintings and works on paper that date from 1996 to today. It offers a chance for viewers to track the progression of Mehretu’s style from early pieces that focus more heavily on mapping and drawing to her sprawling abstractions with innumerable layers of visual information. Some of the most recent works on view also smartly deal with contemporary social issues, as the process begins with photographs—one started with police in riot gear following the killing of Michael Brown, for example, while another began with images of climate change-related firescapes. These images are then blurred and erased beyond recognition before paint and other materials are stacked on, and are then sanded and erased, creating a pentimento surface where older layers peer through newer ones, together forming a cartographic world through which her complex artistic process can be traced.