While the 91st was still encamped in Philadelphia, Alderman Lentz arranged for two omnibuses to take selected soldiers to vote (4). This was apparently controversial; at least, George Hollick later testified to prove he was entitled to vote (4).
On 10 November 1862, a Sergeant Sinexon [sic], and about one hundred and fifty other recruiters, took a band to Baltimore to greet General McClellan. Since McClellan didn't arrive as expected, they went to Dr JRB McClellan's house, and played various patriotic songs. Robert Sinex is the best candidate for being this Sergeant Sinexon (6).
1863 governor's election
On 12 October 1863, the Philadelphia Press published a letter signed by men on duty at Camp Cadwalader, asking Pennsylvanians to re-elect Governor Curtin (3). Three men from the 91st signed it: Matthew Hall (E), John Lentz (F & S), and Samuel Burns (C) (3).
1864 presidential election
According to Thomas Walter, Robert Gray was the only member of company A to vote for McClellan. Twenty-six voted for Lincoln, and about a dozen "remained neutral". (Perhaps they voted for McClellan, but didn't tell anyone!) Gray's reason for voting for McClellan was that he had never voted for any successful candidate for major office, and was worried that Lincoln would lose if he voted for him! (1)
Walter claims that some people in the regiment did prefer McClellan (1). But he thought that no one in the regiment contributed to a proposed testimonial for him (1). Simeon Zane, a corporal in company A, had been so outspoken in favor of McClellan after McClellan was relieved that he was nicknamed McClellan (2). But by 1864 even he had stopped supporting McClellan (1). Walter claims that when McClellan was relieved in November 1862, most of the regiment was pleased, but he wrote this with the benefit of hindsight (2)! (On 25 September 1863, the regiment received a circular from brigade headquarters "[s]uspending all Action in regard to the McClellan Testimonial".)
After the war
In October 1865, veterans, including twelve men who had served in the 91st Pennsylvania, took out an ad supporting a candidate for Pennsylvania State Senate (5).
At least two veterans of the 91st served in the Pennsylvania Legislature. In 1883, Joseph H Sinex was the Representative from the 26th District of Philadelphia. And in the 1889, 1891, and 1893 sessions, John Ennis was a member of the Pennsylvania House of Representatives.