The original call letters were originally based on ship radiocall signs. Non-government boats west of the Mississippi were given the letter K and east of the Mississippi they received the letter W. The original ship radiocall signs were given out by the Bureau of Navigation. When land stations were being tested, the Bureau was also given the task of handing out call letters. They adapted this policy.

I'm not positive why KDKA was the exception to the rule. I am fuzzy on this, but I think the original owner of the license may have been located in another part of the country. Not sure about that.

Ron