Center of the hub

One of the main reasons the battle was fought at Gettysburg is that it is the hub of a network of roads feeding in from all angles of the compass.

(Listed clockwise)
Chambersburg Pike, or Cashtown Road
(now U.S. 30)
Mummasburg Road
Newville Road (now Middletown Road)
Carlisle Road
Harrisburg (or Heidlersburg) Road
(now Bus. U.S. 15)
Hunterstown Road
York Road (now U.S. 30)
Hanover Road (now PA. 116)
Baltimore Pike (now PA. 97)
Taneytown Road (now PA. 134)
Emmitsburg Road (now Bus. U.S. 15)
Fairfield (or Hagerstown) Road
(now PA. 116)

Distances from Gettysburg

Gettysburg is:
25 miles from Chambersburg
28 miles from York
30 miles from Hagerstown, Md.
32 miles from Frederick, Md.
35 miles from Harisburg
38 miles from the Potomac River at Williamsport, Md.
40 miles from the Susquehanna River at Columbia, Pa.
50 miles from Baltimore, Md.
71 miles from Washington D.C.
110 miles from Fredericksburg, Va. using the route taken by most of the Army of the Potomac
112 miles from Philadelphia, Pa.
172 miles from Richmond, Va.
175 miles from Fredericksburg via the Shenandoah Valley, as marched by most of the Army of Northern Virginia
195 miles from New York City