The U.S. labor market strengthened in the weeks before Election Day, as job growth accelerated and the unemployment rate ticked lower.  U.S. employers added 254,000 jobs last month, the Labor Department said Friday. That was the largest monthly increase since March. The unemployment rate slipped to 4.1%.  The numbers beat expectations from economists surveyed by The Wall Street Journal. They expected payrolls to increase by 150,000 in September, and the unemployment...