What does the big bold L stand fro on a dollar bill?

the L does stand for the 12 on the dollar bill. because L is the 12th letter in the alphabet? But there is something else it stand for. Ex. A = Boston, B = New York City, C = Philadelphia, D = Cleveland, E = Richmond, Va., F = Atlanta, G = Chicago, H = St. Louis, I = Minneapolis, J = Kansas City, K = Dallas.