When aides to Rahm Emanuel recently wheeled a cart loaded with tall stacks of his nominating petitions into the city election board’s downtown offices, the more than 90,000 voter signatures were a show of force meant to prove deep grass-roots support across the city for the former White House chief of staff. In reality, his petition drive had received even greater support from many campaign workers who live far beyond the city limits, according to documents filed last week with elections authorities. The Chicago News Cooperative’s review of all of the nearly 5,300 petitions for the Emanuel campaign found that...