I visited as many as 39 post offices in one day. State by state, counting only new, distinct active postal locations (including CPUs) for the year:
Pennsylvania: 74 post offices
Focus/Foci: Rural corners of northern PA
Ohio: 46
North-central Ohio and Cleveland suburbs
Connecticut: 38
Northeast and south-central CT
New York: 21
Southern Tier
In addition to these I also visited discontinued / suspended post offices for documentation purposes as well as historic former post office buildings.
Among privately-operated Contract Postal Units was the operation at the student center at Kent State University in Kent, Ohio:
Kent, OH: Kent State University CPU:

Former sites visited this year include the grand old post office of Hornell, New York, which celebrates its centennial in 2016. Well, I suppose it would be celebrated were the structure not presently relegated to the municipal equivalent of a paperweight.
Hornell, NY: former post office:


There had been a post office in Barton, New York until it was washed away by flooding caused by Hurricane Irene in 2011 and never replaced. It was around here somewhere:
Barton, NY:

Despite some yearning for what we've lost I did find several wonderfully photogenic post offices this year, including that in Milan, Pennsylvania, made all the more stunning during the peak of an August sunset:
Milan, Pennsylvania post office:

Count-wise, I reached a modest milestone this year. My 6,500th post office was New Riegel, Ohio.
New Riegel, OH post office:

See y'all next year! Well, this year. Had a bit of a late start on this post, I suppose.