This is probably a pre-1912 48 star flag. If you study the star pattern you can tell it does not conform to the Executive Order of 1912 which set down the exact sizes, proportions and star arrangements of the American flag. Note the zig-zag rows in the canton compared to the straight up and down rows of a common 48 star flag.

http://www.usa-flag-site.org/forum/a...5&d=1271026675
http://www.usa-flag-site.org/forum/a...4&d=1271026525