Squires - Palmer Family History

I am putting together family history for my children,and am researching the Squires family from Connecticut and the Palmer family from Arkansas.

One ancester in the Squires family, William Harding, was a sea captain from Maine. I believe his father to be Nathaniel Harding, also a sea captain, but can find no hard evidence to link the two.

In the Palmer family, two ancestors were named after American Presidents, James Garfield Smith and Andrew Jackson McGill.
I'm having a very difficult time locating information on Andrew Jackson McGill in Arkansas.

Any help would be greatly appreciated. I'm also willing to share information.