Nathaniel P. Townsend was living with his son Charles Nathaniel Townsend in Sioux City, Iowa in 1889.
Charles stays in Sioux City and is listed in the directory, such as above, until 1891. N.P. is not listed on any directories after this date for this city.
The search continues as I cannot locate N.P. in any cemetery in Woodbury County, Iowa as of yet.