He was born in 1831/32 (4 (29 in 1861)).
He enlisted and was mustered into service as a private on 7 December 1861, at Philadelphia, Pennsylvania (1, 4). He was a private in company B (1, 5-7).
According to Bates, he deserted on 19 August 1862 (1, 4).
On 28 July 1863, he was reported as having been dropped because he was missing in the campaign (probably after 11 June 1863) (2). He was a private in company B (5-7).
1 Bates, Samuel Penniman. History of Pennsylvania volunteers, 1861-5. Harrisburg: B. Singerly, state printer, 1869-71. 5 volumes. 'Ninety-first regiment', volume 3, pages 186-233. (In the roster) (William Rider)
2 consolidated morning report, 91st PA, 28 July 1863 (Private Rider [?])
3 company B, descriptive roll, entry 35 (William Righter) (no information)
4 Civil War Veterans' Card File, available at the Pennsylvania State Archives, searched 31 May 2004 (William Rider)
5 index to compiled service records of volunteer Union soldiers who served in organizations from the state of Pennsylvania (William Rider)
6 index to compiled service records of volunteer Union soldiers who served in organizations from the state of Pennsylvania (William Riter)
7 index to compiled service records of volunteer Union soldiers who served in organizations from the state of Pennsylvania (William Righter)