From an article in the Idaho Statesman (which cites Clayton Cramer and John Lott).
Between 1986 and the present days:
States prohibiting concealed carry, with no licenses to do so available, shrank from 16 to 0.
States allowing permits on a discretionary “may issue” basis shrank from 25 to 9.
States allowing permits on a “shall issue” basis rose from 8 to 36.
States allowing concealed carry with no permit rose from 1 to 5.
All this over a period when both total homicides and gun homicides have fallen by about half.