Do I have to hire an attorney in the same city or county where the injury occurred?
Find an attorney who handles primarily your type of case.Rather than focusing on the location of your attorney in the state its better to focus on the type of law the attorney is primarily handling. In my opinion it is best to not go with a "jack of all trades" attorney for an injury case. You want one that does primarily injury and not much else.
Don't worry about how far the attorney is from the injury site.You are most likely not paying your injury attorney by the hour but rather on a contingent fee. It's your attorney's problem how to get back and forth to an injury site if needed. If your attorney needs to file suit and take the case to trial they will determine if they should associate with a local attorney for trial purposes. If they do, they will split their fee with the local attorney. It will not cost you anything. Then you have two attorneys for same contingent fee. One that is specialized in injury cases and another who may be more familiar with the local protocol for that court.