McPherson Ridge is a landform used for military engagements during the 1863 Battle of Gettysburg, when the I Corps of the Union Army had a headquarters on the ridge and was defeated by the Confederate division of Major General Henry Heth.^[5] The ridge has terrain above ~530 ft (160 m) and is almost entirely a federally protected area except for township portions at the southern end and along Pennsylvania Route 116, including a PennDOT facility. The northern end is a slight topographic saddle point on the west edge of Oak Ridge, and summit areas above 560 ft (170 m) include 4 on/near the Lincoln Highway, a broader summit south of the Fairfield Road, and the larger plateau at the northern saddle.^[2]

In 1747, the Nichol's Gap Road ^[6][7] (later "Hagerstown Road", now Fairfield Road) was built over the ridge,^[8] followed by the road on the north that became the 1809 turnpike from Gettysburg to Black's Gap^[9][10] (extended to Chambersburg in 1810).^[11] In 1835, Middle Ridge had the middle of three 1835 railway cuts (cf. Herr Ridge & Seminary Ridge) excavated for the Tapeworm Railroad. In the 1850s, the Old Mill Road across the ridge had been established northwest from the Hagerstown Road past the J. Herbst farm along Willoughby Run.^[3] During the 1858 Hopkins survey, the "H. Dustman" farm was on the ridge along the turnpike's south side and east of the "Toll Gate",^[12] while along Willoughby Run on the ridge's west slope and north of the railway bed were the farms of "Heirs of Wm McPherson" & "J. B. McPherson".^[3] After moving back to Gettysburg in 1856, attorney Edward McPherson inherited a farm in 1858^{[citation needed]} which had 66.5 acres (26.9 ha) by 1863.^[13] On June 30, 1863, John Buford's Union cavalry camped 400 yd (370 m) east of the ridge prior to the Battle of Gettysburg.^[14]