Sentence:  These permit the limited number willing to abandon their automobiles for long hikes to visit some of the most rugged terrain in Southern California. Major resort centers with substantial year-around residence (and much <WSD>commutation</WSD>) occur in the western Santa Monica Mountains, the San Bernardino Mountains, and around Idyllwild in the San Jacinto. 
Meaning of the word marked with <WSD> tags:  The process or habit of journeying to and from work on a regular basis; commuting.