JA2C-
First off, CONGRATS!! Exciting news indeed on the new family member...
You have many options:
1. Interview as scheduled. If selected, you can decline the job offer. Other offices can use (you can get credit for) the previous interview so you may not have to repeat the interview again for another office.
2. Decline the interview and go back in the "pool". Gather intel. Call the local office manager and express interest. Ask if they intend to hire anyone soon. Sept is the end of the fiscal year and is the "active" month for hiring. Then wait it out..
3. Revise your online app to narrow your locations to only the office(s) closest to your home.
4. Take the "bird in the hand" and pursue the interview and job offer if it comes. Get your foot in the door. Once you are "in", you can eventually transfer to another office after you put in some time there (at least a year). "Cooperate and Graduate" the first year, since you would be on probation.
Gubment hiring is fickle. Some get hired quickly when others have a long wait. Took me FIVE years to get hired. Mainly luck and timing.... A little patience and persistence (networking) may pay great dividends...