From The New Yorker:
Only about ten Democratic staffers had access; entry required an elaborate ritual—fingerprint scanners and codes punched into a keypad. The room was large, and unremarkable except for an enormous printer and an array of computers with big double monitors. On the screens that spring day were detailed maps of Chicago, and Obama and a Democratic consultant named John Corrigan sat in front of a terminal to draw Obama a new district. Corrigan was the Democrat in charge of drawing all Chicago districts, and he also happened to have volunteered for Obama in the campaign against Rush.
Like every other Democratic legislator who entered the inner sanctum, Obama began working on his “ideal map.” Corrigan remembers two things about the district that he and Obama drew. First, it retained Obama’s Hyde Park base—he had managed to beat Rush in Hyde Park—then swooped upward along the lakefront and toward downtown. By the end of the final redistricting process, his new district bore little resemblance to his old one.
Rather than jutting far to the west, like a long thin dagger, into a swath of poor black neighborhoods of bungalow homes, Obama’s map now shot north, encompassing about half of the Loop, whose southern portion was beginning to be transformed by developers like Tony Rezko, and stretched far up Michigan Avenue and into the Gold Coast, covering much of the city’s economic heart, its main retail thoroughfares, and its finest museums, parks, skyscrapers, and lakefront apartment buildings.
African-Americans still were a majority, and the map contained some of the poorest sections of Chicago, but Obama’s new district was wealthier, whiter, more Jewish, less blue-collar, and better educated. It also included one of the highest concentrations of Republicans in Chicago.