Is Washington International University -- P.O. Box :61707,
King of Prussia, PA 19406 USA accredited ?

No,it is not.They are known as a diploma mill.
Washington International University - Wikipedia, the free encyclopedia

Accreditation doesn't matter but what matters is what the wiu graduate can offer to the world. Most of wiu graduates are quite good and hard working on their positions.

Wiu saves the poor who cannot afford expensive fees by most of so called accredited universities. Wiu also gives opportunity to those who cannot manage to be in class full time. Above all wiu's are properly arranged and administered by the very same professors from those so called excellent universities but too expensive.

I repeat, accreditation is nothing other than what the graduate is able to do in the market. I have seen some of them and are doing quite good than those from so called well known universities.

Yes it is.