Mapping 3-digit US postal codes

Hello -

I am trying to map 3-digit postal codes (i.e., just the first three digits of the postal code) in the US. 

I have created a column which pulls the left three digits - I have confirmed that this column is in text, categorized as a postal code and that the zero in the front does not get dropped.

However, the map displayed does not chart any that start with a zero (see below highlighted in yellow). Has anyone run into this problem before and can help advise?