It was made in Philadelphia, the "P" mintmark was not used on a half dollar until 1980.
Depends entirely on year, mint mark and condition.
Look at the date again and post new question, the first Walking Liberty half was 1916.
It's not a mint mark. It's the monogram of A. A. Weinman, who designed both the "Mercury" dime and Walking Liberty half dollar.
The 1946 walking liberty half is a common date, but because it is 90% silver, it is worth around $10.50 in common circulated condition.
Exactly $100.
Walking Liberty halves were struck at all 3 mints that were active at the time. No mint mark = Philadelphia, S = San Francisco, D = Denver
The mint mark position on all Walking Liberty halves after 1917 is the 8:00 position. Possible letters are: Blank = Philadelphia D = Denver S = San Francisco
The 1920 Half Dollar - aka - Liberty Walking - mint mark of "D" or "S" would be located on the reverse side, just to the left and above the "H" in half dollar.
The mint mark on a 1936 Walking Liberty half dollar is located on the reverse [tails] side of the coin in the little "valley" just to the left of the word "HALF" near the edge of the rim.
1940 makes it a Walking Liberty half, so the mint mark is on the reverse (tails) side, directly below the leaves of the branch, to the left of the word "half." D is Denver, S is San Francisco, and no mark is Philadelphia.
It's the designer's monogram, Adolph Weinman. All Liberty Walking half dollars have it.
W on a Walking Liberty half dollar is the designer's initial (A. A. Weinman). The mint mark location is on the back at roughly the 8:00 position - blank, D, or S.