City Halls are not happy and it's the widening wage gap that mayors blame. The tax revenue that towns and cities need to keep operating, is dwindling as jobs created since the recession are paying less than jobs lost in the recession, a report from the U.S. Conference of Mayors said on Monday.The report also forecasts that middle-income households, the backbone of an economy, will lag further as high-income families continue to sweep up most of the wage gains. Although almost three-quarters of cities today have more poor households than wealthy ones, income growth is concentrated at the top, the report said. The wage gap has nearly doubled from where it stood almost 12 years ago, the last time the nation struggled through a recession. The current gap stands at 23 percent, versus 12 percent during the 2001-2002 recession. The Conference of Mayors set up a task force, led by New York City Mayor Bill de Blasio, to recommend national and local policies to give everyone opportunity.