Especially the Great Mills PO is now in LP according to that map.
So when you google Great Mills and select map, that outline shows it as in GM. BUt when you do that for Lexington Park, the GM borders is right, but it cuts LXP off to the south at Hermanville Road. None of SLP shows up..... Off to the GIS I go
Ah, so go into the GIS (County Geographic Information System) and it gets even odder. Select the Zip Code and Town Labels lists on the layer selection (upper right corner) Then zoom in around the GReat Mills Road Rt 5 intersection. Looks like that area right at the post office is an island of Great Mills not connected to the larger part..... And that Southern GReat Mills actually goes down the south side of Flat Iron Road to encompass Deer Run and Greens Rest Farm Subdivision.....
Oh, and GReat Mills High SChool is another island of GReat Mills cut off from the rest.......
stmarysmd.maps.arcgis.com