The Tompkins County Department of Assessment has broken down Tompkins County into seperate neighborhoods or market areas.  These neighborhoods were created by analyzing sales of real property.  These sales were then delineated according to differing market factors (such as school district and view) within each municipality.

The neighborhood code is a 5 digit number.  The first 2 digits refer to the municipality's State Wide Identification System (SWIS).  For example the SWIS code for the Town of Caroline is 502000 or for explanation purposes 50-20-00 (50 for Tompkins County, 20 for Town of Caroline, 00 for no village present).  The neighborhood codes for Caroline will thus start with 20.  The 3rd digit of neighborhood codes is always a zero.  The 4th and 5th digits explain the "value" of the neigborhood.  The lowest valued neighborhood would be 10 and as the value of the neighborhood increased, so would that value to 20.  For example, there are 3 neighborhoods in the Town of Caroline: 20010, 20020 and 20030.  Neighborhood 20010 is the lowest valued neighborhood.  Neighborhood 20020 is valued higher than 20010 but less than 20030.

Now there are some exceptions to this.  If the neighborhood consists of lakefront properties the last 2 digits will always be a 40 regardless of how valuable the lakefront is compared to other neighborhoods.  Also, the neighborhoods in the city of Ithaca do not follow this numbering scheme.