A field value may be added that includes a prefix followed by a space. For example, a state prefix and a space can be added to a city field in the attribute table. The image below shows the City field being added with a prefix value of TX and a space.
With the Field Calculator, add a field with a user-defined prefix or use an existing field from the attribute table.Adding a user-defined prefix
"<The prefix>" + " "+ "<the field>"
"<The prefix>" + " "+ !<the field>!
If the attribute table has existing fields to be used as the prefix for another field, concatenate the prefix field and the field to be prefixed. For more information on how to concatenate fields, refer to How To: Use ArcMap to concatenate fields in a table.