Taming the wild west was singlehandedly done by security fence. Barbwire security fence kept cattle and other livestock from venturing onto others property as well as limiting trespassers from roaming freely.
Nowadays, security fence still defines boundaries and gives security to business and home owners which establish a 'do not cross barrier' keeping in or out whatever may be. Can you imagine prisons, zoos, military bases, school, etc. without security fence? Security fence keeps people/animals contained or people/animals from gaining access to property.
Notice the security fences along the highways to keep deer off the road and security fence around daycare facilities. As the threat of safety concern grows, security fencing is here to stay in Denver.