Throughout U.S. history, there have always been signs that a major downturn was coming, and that is precisely what we are witnessing right now.  Tax revenues are way down, demand for trucking services is way down, demand for cardboard boxes is way down, the money supply is shrinking at the fastest pace in modern history, and the Conference Board's index of leading economic indicators has already declined for 15 months in a row.  At this point, anyone that cannot see what is coming has got to be willingly blind.  The following are 7 trends which indicate that economic disaster is approaching very rapidly…