City Councilor Charles Yancey has represented Boston’s District 4 since the district was created in 1983. In every election since then — both preliminaries and finals — Yancey has taken the top spot at the polls. But all that changed in the September 8 preliminary election, when newcomer Andrea Campbell trounced Yancey, 58 percent to 34 percent. Campbell ran strong across the entire district, which includes large pieces of Dorchester and Mattapan, with slivers of Jamaica Plain and Roslindale. But the size of her victory came from running up huge margins in the highest turnout precincts — precincts that also tended to have the largest white populations in the predominantly minority district.

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