How long does it take for the us postal service first class to mail a package from Florida to Massachusetts?

3 business days on most occasions, 4 if they're super swamped.

Two days on the average from North to South. One day if the sender and receiver are both within the upper or lower half of the state.

http://www.fewtek.com/texas.htm

First Class Mail is delivered in three fo five days.

First Class Mail is delivered in three to five days.