The surname Maverick can be traced back to 16th century England as you can see at
http://tr.im/si65. It was originally spelled Mavericke. The first Maverick arrived in the US in the early 17th century as shown at
http://en.wikipedia.org/wiki/Samuel_Maverick_(colonist). You'll find the distribution of the surname at
http://www.ancestry.com/facts/maverick-family-history.ashx.