People came west for a wide variety of reasons. The earliest transplants came to escape the confines of the east; they were looking for the wide open country and the ability to stay away from people. These people were the trappers, the hunters, and the explorers. They were more solitary, but their friendships were important to them. In the early isolated west, friends were all that you could depend on, but you did not dwell on it. Western friendship were only for when you needed help or wanted to share when you were flush.
The next wave of settlers was seeking riches. They went west in search of gold and silver. They surged to where ever the latest rich strike was found. They set up small vibrant towns where ever the ore could be found. When the ore dried up, most of them moved on to another strike. They seldom moved as a coherent group, usually a small group of partners, occasionally a family unit, but frequently as individuals. They moved from place to place, re-forming friendships when they ran into each other, but leaving friends as easily as they abandoned towns in search of riches. Western friendship continued to respond to need or to share wealth.
The robber barons, great and small, were the next great migrants. They followed the railroad, snapping up land on either side of the rights-of-way. They built towns at the watering stops to control trade between the east and the hinterlands of the west. They built stores to support the farmers and traders and saloons to take money from the cowboys and soldiers. People in the towns banded together to combat the law of the gun. Even while they civilized the west they were shaped and molded by it. They were separated from their families and their pasts. And they continued to move as the settlements grew around too large around them. Their friendships survived over long distances.
The dust bowl and depression brought the next group west; farmers blown off their lands by drought and winds. They gave up, surrendered what they and their fathers had worked so hard to build and moved west in search of the Promised Land. They moved as family groups and individuals. They moved as far as they could and put down their new roots where ever they landed. Fertile land was available as was work for anyone that wanted it. Many people left the closed factories back east for that work in the sunshine. In shame they broke contacts with their deserted friends and family and made new friends in their new homes. Again, western friendships were quickly formed.
Even today the migration continues. People move west for fame in the entertainment industry. They move west for the high paying jobs in aerospace or tech. What ever they are moving to, they leave their friends and families behind. They arrive to find that most people are also new arrivals. No one stays in place long enough to become a native. When the company closes, or the job becomes boring, or another place just becomes more attractive, you move on.
Western friendships continue to reflect the transitory nature of the population. Friendships are formed quickly and are not torn apart when people move. They either stay in touch or the friendship hibernates until they run into each other in another place. There is no guilt in not talking to an old friend in years; when you see each other again you catch up and either resume the friendship or move on. In either case it is part of the lifestyle that people out west accept as a natural part of their new lives.