Michael Harshaw was appointed postmaster at Galum, IL on Jan 21, 1862. Abraham Lincoln had been postmaster some 30 years earlier and got paid about $20 a quarter. I don't know the basis--whether it was a flat salary or based on the money the postmaster collected.
Ancestry has a some explanation . As noted, the appointment was political (remember the movie "Lincoln") which links up with grandfather's bio of Michael.
But why "Galum"? Cutler, IL was only developed when the railroad came through, which was after 1862. My only clue is a "Galum Church Road" which currently runs west from the Pinckneyville area towards Cutler. Today it ends in an area which was mined, but assuming it was a continuous route in 1862 it would be route 15 which runs just north of Cutler, near the original location of Michael's church.
So was Michael's church the original "Galum Church? No, it seems there was a Galum church founded in 1854 near Pinckneyville which burned down in 2005,but the cemetery still remains. So where was the postoffice, near the Galum church or the Cutler church. Not clear.