Kathie Ann, I just found this posting of yours that dates back to Apr. 2000, so I assume you may have obtained additional information on Nathanial Carlow by now. However, just is case I thought I would pass along my non-proven findings on this Carlow family.
I believe Nathanial Hudson Carlow is the son of James Carlow and Polly Hudson. James Carlow (2) is the son of James (1) Carlow and Mary Dickey.

James (1) Carlow is found in the 1790 and 1800 census of German Twp, Fayette Co PA. James was in the Rev War. Found in the Roll of the Third Company in the Eighth Battalion of Cumberland Co Militia PA. The family of James and Mary moves to Jeffereson Co. Oh, Ohio Co. WV, Belmont Co. Oh and then on to Muskingum Co. Oh between 1800 and 1830. Their son John appears in Madison Twp. Guernsey Co. Oh in 1811. James (1) disappears from records in 1810, 1820 and Mary appears on the 1830 Blue Rock Twp. Muskinghum Co. Oh census. I assume James (1) died during that period. Other children: Katherine (my line married Jacob Coleman), John and Agnes (married David Parshal).

James Carlow (B: PA per 1860 census) and Polly Hudson (B: NY per 1860 census) are married I believe in Jefferson Co. Oh before 1813, where Nathanial Hudson Carlow was born on December 20, 1813. In 1850 James and Polly are found in the census for Blue Rock Twp Muskingum Co Oh. Other children: Jesse J., Horace W., Abdallah, William D., James Curtis and John.

Nathanial Hudson Carlow and Mary Hannah Richey are married in Monroe Co., Oh on 11/9/1837. I believe they are the N. H. Carlow family in the 1850 Platte Twp, Andrew Co MO census. Chidren: James Hudson, Nathaniel, George, Mary (Hannah M.), Caroline F., William A.

I hope this helps get you on your way investigating this Carlow line. As I mentioned above I can not prove these relationships as they are piecemealed together from various misc. sources and census records.

Bill