They're not exactly lemmings, but Americans have always headed for the coast.
Fifty-three percent live and work in the narrow coastal fringe that accounts for just 17 percent of the land mass in the contiguous 48 states. And of course, many more leave the broad midsection at vacation time to puddle around in tide pools, fish for the big one, and hit the surf.
According to the National Oceanic and Atmospheric Administration (NOAA), population along the southern California coast (from Santa Barbara to San Diego) has been increasing by about 4,000 people a week. In Florida, the weekly flock of newcomers is 4,400.
Fourteen of the 20 largest US cities are in the coastal zone, reports NOAA, and population density along the East, West, and Gulf coasts will have increased from 187 people per square mile in 1960 to 327 by 2015 - three times the national average.
And with that population growth comes booming development of the type now facing nature-related problems in Oregon. Every week, this includes 8,700 new single-family homes and 5,800 housing units in multiunit dwellings going up in US coastal zones.
"Ironically, as the coastal population grows, the natural features that may have attracted people to the coast are lost or diminished," warns a NOAA report. "The challenges of assimilating increasing numbers of people along the coast while minimizing the potential environmental degradation from development are considerable."