Unlike the Park Cities or even neighborhoods like Devonshire or Pagewood, today's Preston Hollow doesn't have clearly defined boundaries. In fact, it's easier to say what it isn't than what it is.
Preston Hollow is not north of Royal Lane despite what someone selling a house near Forest and Hillcrest may claim. If the house is in the Carrollton-Farmers Branch ISD, it isn't in Preston Hollow.
Preston Hollow does include parts of 4 zip codes: 75220, 75225, 75229 and 75230. If a property isn't in one of those zip codes, it isn't Preston Hollow. The problem is that those zip codes also extend outside of Preston Hollow. I guess it would be too difficult for the folks running sales statistics to simply contain the area with a map. Somewhat easier would be to include only properties in the MLS area 11. If the search were confined to those 4 zip codes and MLS area 11, about 75% of the properties would actually be in Preston Hollow. .