Osprey are found over almost the entire planet.  Osprey from this region fly to South America to winter. 
Some possibly stop in Florida or some of the island nations in the southern Atlantic.  The day you should start looking for them to return is easy to remember.  It is St. Patrick's Day.  Last year, the first one I saw was on that day.  This year, the first one I saw was two days later.  One pair has picked a nesting site that is very easy to view from a passing car (although you should be careful not to become too distracted).  For those of you who live in Calvert County and commute to Washington every day, you are in for a treat.  Traveling south on Route 4, as you come across the bridge over the Patuxent (at Wayson's Corner), look at the top of the pole that supports the first highway sign south of the river.  A pair used that site for a nest last year and have returned this year.  It is an ideal location, overlooking the fishing grounds and well protected from predators.  Of course, they have to put up with the traffic noise - but so does everyone living within ear shot of Route 4.