Great question, Doug.  This is one of my most wanted passerines in Maryland along with Yellow-bellied Flycatcher, which seems to have a similar migratory pattern.
 
One great way to hone in on locations and timing is using eBird (www.ebird.org): you can query map locations by state(s), month, year(s) and species.  This can be great for finding the locations with the highest number of records for a given species in any month of the year.
 
Ross 

--- On Fri, 8/20/10, Doug Norton <> wrote:


From: Doug Norton <>
Subject: [MDOSPREY] places to look for migrating Philadelphia Vireo?
To: 
Date: Friday, August 20, 2010, 11:21 AM


Hello all,  I've noticed on past postings around labor day that this vireo seems to move through the region around then.  It's eluded me for years (current jinx bird) and I'd love to get a look at it this year -- any suggestions for places within a two hour radius of DC that might increase my chances?  Any and all suggestions welcome, as well as tips on habitat, behavior, or alternate opinions of time of year when best seen.  Thanks.