Mapping Commuting Zones from Counties for US 1990 Data in ArcMap?

Question

This question follows Seeking 1990 US Commuting Zone shapefiles?

I am attempting to map US commuting zones as defined in 1990. I have successfully mapped counties from a county shapefile obtained here. After completing the following advice, I get the error message below:

In the xls, there is a column called CZ90 which I assume is the 1990 commuting zone code. Once you've joined XLS to FIPS shapefile, use the dissolve tool with the CZ90 field as the dissolve field to output a shapefile/feature class with one polygon per commuting zone.

I used the dissolve tool and checked CZ90 as my only field; however, I get the following error message. It appears that I correctly joined the CZ90 excel file with the FIPS shapefile.

How can I successfully dissolve the counties into commuting zones?

Answer 1

It's possible the ArcGIS tool doesn't like the joined Excel fields. Try one of the below suggestions before you run the dissolve:

1. Removing the join and using the Join Field tool which permanently adds new fields (instead of Add Join which just creates temporary virtual fields) or;
2. Adding a short integer column to CO99_D90 called CZ90 then using the field calculator to copy the CZ90 data from the xls CZ90 into the new CZ90 then remove the temporary xls join.

Then use the new CZ90 field for the dissolve.