Original: These stories typically involve "frontier" colony worlds (colonies that have only recently been terraformed and\/or settled) serving as stand-ins for the backdrop of lawlessness and economic expansion that were predominant in the American west.
Simplified: These stories are often on "frontier" colony worlds (colonies that have only recently been terraformed and\/or settled) serving as stand-ins for the backdrop of lawlessness and economic expansion that were predominant in the American west.