It is the "USS MISSISSIPPI". At : http://www.navsource.org/archives/01/41a.htm it is stated that the “E” stands for Mississippi (BB41). There is a 1918 picture with the letter. On an other site, I found the same picture as above which stated that it was taken at a 1929 visit of the MISSISSIPPI to Vancouver. However, I found several pictures taken between 1920 and 1930 without the letter "E".

"New Mexico" class battleship, more likely before mid-1930s. Signal flags and engineering "E" on the stack might be clues to ID. I have Fahey's, but earliest is 1939 and Janes Fighting ships (1918 & 1942), none which would help positively ID this classic battlewagon.

This is one of the three IDAHO Class BB's. The others are the MISSISSIPPI and NEW MEXICO. Note the enclosed former 5-inch gun positions at the bow. These are a dead givaway to the IDAHO's.