Driving standards in the US are very high, and its not unusual to find a high driving test failure rate in several states. You can find a complete list of the driving failure rates according to states listed at the GMAC site here. GMAC carries out an unbiased survey based on every state, to rate state statistics for car insurance purposes. As a result, the survey has stated that the most unfit drivers are based in New York, while the most careful drivers are in Kansas. Average test scores per state can also be found at this link here. You can also get in touch with the DMV of each state for specific information.
For more info, see What to Do to Avoid Automatically Failing a Driving Test