Gapers' Block Meaning

(chiefly US and Canada, idiomatic) A traffic jam resulting from motorists slowing to look at a motor vehicle collision or other roadside distraction.

Example: 1967, "Above It All," Time, 10 Mar.:
  In the lingo of the traffic reporters, "gapers' block" is a tie-up caused by motorists slowing down to gape at an accident.
2001, "Rocky Road Rocky Mountain National Park boasts as ear-popping drive full of peak experiences," Wichita Eagle (Kansas), 25 Mar., p. 1G:
  In the pretty, tranquil valley, elk were feeding just off the highway, creating a gapers block.