It's called an Exact Match Domain: houstonautodetailing.com or bestbusinesscards.com or buyiphonenow.com
What I would recommend is go into the Google Adwords Keyword Planner and see what keywords get searched the most.
For instance, I live in Houston:
- car detailing houston gets 480 searches a month
- auto detailing houston gets 260 searches a month
- houston car wash gets 210 searches a month
- houston detailing gets 20 searches a month
So it would make sense for my EMD to be cardetailinghouston.com because that's the highest volume of traffic.
I wouldn't want to put houstondetailing.com because only 20 people search that per month.
But, an EMD will not make or break your business/site.
Sure you'll get a
slight advantage, but if you at least follow SEO best practices, you'll rank well in Google.
Here's some great resources:
-
Local Search Ranking Factors 2014 - Local SEO and How to Rank in Google - Moz
-
The Exact Match Domain Playbook: A Guide and Best Practices for EMDs - Moz