Depends. If you lived in New York and sent a letter, to, say, Tokyo, it would take a while........
Usually two or three days, but longer times are not unheard of even for short distances.
It depends on how far you're sending it..Here is a link to USPS website that gives estimated delivery times for different types of mail...
depends on the destination of the mail it is going to Columbus , Ohio from rodchester, New York
usually 2-3 weeks from OKC