I ”apprenticed” on 2 large jobs over a 9 month stretch with a finish carpenter
born in 1900.  In the Philadelphia area.  In 1974 we were getting 2X lumber
anywhere from 1-3/4 to 1-9/16" thick and similar variation on width.  In the mid
80’s it seems to stabilize at 1-5/8”.  then in the 90’s it went to 1-1/2”.

With more accurarte cutting technology, are they cutting it thinner before
finishing?

Ed Minch