Safe Trick or Treat Beginning at 10 a.m. today, Mill Street in Grass Valley will be blocked off, allowing pre-school children to trick or treat at downtown businesses in this annual tradition organized by the Downtown Association. There is a costume and window contest, which Tess’ Kitchen and their Batman theme won last year. The event is free to the public for all pre-school children and ends at noon. Nevada City Trick or Treat Similar to Grass Valley’s event earlier in the day, this Nevada City event has Broad Street blocked off downtown from 5 p.m. to 8 p.m. for …