Silk hats replacing beaver fur hats:
When Jason Coolidge (actor Frank Ferguson) is sitting at the dining table with characters Flip Flippen and Johnny Caldwell, he says, "I've trapped and traded the whole Northwest, until the silk hat came along and run the beaver out of business".
This is a historical reference to the changing fashion of men wearing silk hats, instead of beaver fur hats. The beaver hats had been in style since the 1500's, but by the mid 1800's, men preferred to wear silk hats. The trade for beaver pelts went into decline, and trappers like Jason Coolidge were out of business.