CHONGQING, China — Until recently, visitors who arrived at the urban planning exhibition hall here were greeted with a high-tech shrine to Bo Xilai, who served as the municipality’s charismatic Communist Party chief. A video recounting Mr. Bo’s “smash black” crackdown on organized crime featured mug shots of gangsters emblazoned on tombstones. Maoist revolutionary songs blared from speakers in the “red culture” wing. Lasers zipped across the “honest government” gallery....

...Today, the entire floor is cordoned off.

The sudden demise of the exhibit reflects the headlong race under way to expunge all traces of Mr. Bo and his political fingerprints from the city he spent five years governing. In seeking to airbrush Mr. Bo out of public life, party mandarins in Beijing have dusted off a strategy perfected during the Cultural Revolution and further tweaked during the political purges that followed the Tiananmen Square protests of 1989....