3-7-77 was the symbol used by the Montana Vigilantes in Virginia City, Montana. People who found the numbers '3-7-77' painted on their tent or cabin knew that they had better leave the area or expect to be on the receiving end of vigilantism.
The numbers represent the dimensions of a grave, 3 feet by 7 feet by 77 inches
If a crook didn’t leave town within 3 hours, 7 minutes and 77 seconds, they would find themselves residing in a grave.
Of the original Montana Vigilantes, 3 were lawyers, 7 were merchants and 77 were miners.
The first Masonic meeting in Bannack, Montana took place March 7, 1877. Many members of this lodge were also the original Vigilantes.