How many battleships were built by Us during World War 2?

There were 2 North Carolina class ships completed in the late 30's, 4 South Dakota class ships completed in the early part of WW2, and the 4 Iowa class ships completed in 1943-44... so depending on your exact timeframe, approximately 10 that were completed.

Additionally, there were 2 more Iowa class ships that were never completed, and 4+ Montana class ships that were never built (basically enlarged Iowas with an extra turret, lower speed, and thicker armor)