LIghter, 9:20 am on26 July.
References pointing to low incidence of violence in the old west:
Roger McGrath, 1984, " Gunfighters, Highwaymen, and Vigilantes: Violence on the Frontier," Univ. California Press
"The frontier-was-violent authors are not, for the most part, attempting to prove that the frontier was violent. Rather, they assume that it was violent and then proffer explanations for that alleged violence" (p. 270).
Eugene Hollon writes that the western frontier "was a far more civilized, more peaceful and safer place than American Society today."
W. Eugene Hollon, 1974, "Frontier Violence: Another Look." Oxford University Press.
Terry Anderson and P. J. Hill affirm that although "the West.... is perceived as a place of great chaos, with little respect for property or life," their research "indicates that this was not the case; property rights were protected and civil order prevailed. Private agencies provided the necessary basis for an orderly society in which property was protected and conflicts were resolved."
Anderson, Terry, and P. J. Hill, 1979, An American Experiment in Anarcho-capitalism: The Not So Wild, Wild West. Jour. Libertarian Studies 3:9-29.

Wagon trains established a constitution or ground rules before setting out. Ostracism and banishment threats were sufficient to correct behavior.
Miners in California formed associations and contracts with each other.
References from a brief article in http://www.independent.org/publications/tir/article.asp?a=803.

A book often cited for violence proves the opposite if read; "The Vigilantes of Montana," Prof. Theodore J. Dimsdale, 1866.
Businessmen and ranchers in Montana organized and hung, jailed, and rooted out thieves, rustlers, and killers in the state, insuring safety for its citizens. This book has been reprinted many times, it is an interesting and very readable history of bringing peace to an area without government law.
The full title: "The Vigilantes of Montana, or popular justice in the Rocky Mountains, being a correct and impartial narrqative of the chase, trial, capture and execution of Henry Plummer's road agent band, together with accounts of the lives and crimes of many of the robbers and desperadoes." Printed on Virginia City, Montana.
In the book, the vigilantes are not named, and the identity of some is still uncertain, others identified themselves at later dates, some were prominent owners of ranches and businesses, others entered politics. They made Montana safe for those who came to make a home in that region.