By: Sarah Kliff 

How much you pay for health care often depends on one key fact: where you live.

A new study of more than 1 billion medical bills makes this fact abundantly clear. It shows huge variation in the price of basic medical procedures like ultrasounds, annual physicals, or cataract removals.

Consider this: An ultrasound for pregnancy costs an average of $183 in Canton, Ohio. But drive an hour north to Cleveland, and the average price more than doubles to $522.

This problem isn't unique to Ohio. A new study published today in the journal Health Affairs hows that massive price variation exists all over the country. Each city or state seems to have at least some prices that are sky-high when compared to the national averages.