Original User: dougstanley

Returning to use of ArcMap after 5-year absence and I've forgotten a few things... I am using ArcView 10 and, unfortunately, under a tight deadline. Please help.

I want the software to apportion the population projection for the split MSAs to the appropriate Sales Territory. Many moons and versions of ArcView ago I knew how to do this. Any help appreciated.

Returning to use of ArcMap after 5-year absence and I've forgotten a few things... I am using ArcView 10 and, unfortunately, under a tight deadline. Please help.

**Layers**: Layer 1 contains polygons of sales territories. Layer 2 contains polygons with population projections by MSA.**Problem**: Sales territory boundaries sometimes cross (or divide) MSAs. Using the Geoprocessing tool, I can clip the MSA to adhere to the territory boundary, but the value in the population field remains unchanged.I want the software to apportion the population projection for the split MSAs to the appropriate Sales Territory. Many moons and versions of ArcView ago I knew how to do this. Any help appreciated.

I'm not aware of any tool that will do this automatically for you, but it seems like you should be able to calculate the final population by multiplying the initial population by the proportion of the initial area in the new area. For example, if your final area is 60% of the initial area, then the final population should be 60% of the initial population.

1.) Calculate the initial area in a new column so it won't change after your overlay (ie. not in the automatically updated GDB Shape_Area column)

2.) Overlay your polygons

3.) Calculate the new area (or if you're using a GDB there will be an updated area column)

4.) Calculate the proportion of the initial area in the new area (new area/initial area)

5.) Calculate the new population (initial population * area proportion)