I suspect national park attendance: https://irma.nps.gov/Stats/SSRSReports/Park%20Specific%20Reports/Annual%20Park%20Recreation%20Visitation%20Graph%20(1904%20-

I suspect national park attendance: https://irma.nps.gov/Stats/SSRSReports/Park%20Specific%20Reports/Annual%20Park%20Recreation%20Visitation%20Graph%20(1904%20-%20Last%20Calendar%20Year)?Park=YOSE https://irma.nps.gov/Stats/SSRSReports/Park%20Specific%20Rep... has grown much faster than population, due to heavy advertising by national parks and a general increased awareness of visiting national parks as a "thing to do" on vacation rather than e.g. going to Disney Land.