The 143rd Pennsylvania Infantry served as a member of Stone’s Brigade in Doubleday’s Division of the First Corps, Army of the Potomac, a Fighting 300 Regiment. The unit was commanded by Colonel Edmund L. Dana (1817-1889). Dana was a graduate of Yale, and a veteran of the Mexican War. He was also a lawyer in Wilkes Barre. Dana was promoted to command of the brigade and Lt. Col. John D. Musser (1826-1864) took command. Under Dana's command the 143rd brought 515 men to the Gettysburg Battlefield and among them 21 were killed, 141 were wounded and 91 went missing.
The 143rd Pennsylvania Infantry Monument is located along 
Hancock Avenue (RD310), on the right or east side of the road if traveling traveling north, just ahead or north of the 13th Vermont Infantry Monument (MN249-C). The part of the road comes out of a bend. This area is an absolute beehive of activity as this site represents the best of what Gettysburg has to offer, both historically and monumentally. 
Parking is plentiful and is available road-side at intermittently enlarged shoulder cut-outs, usually marked with white striping. Be sure to keep vehicles off the grass or you will be ticketed by park police. I visited this monument on Tuesday, August 7, 2012 at approximately 3:26 P.M. I was at an elevation of 579 feet, ASL. I used a Canon PowerShot 14.1 Megapixel, SX210 IS digital camera for the photos.
Often, state regiment monuments are also accompanied by secondary monument which designate positions maintained from July 1-3, 1863 as well as flank monuments to delineate the ends of troop lines. The primary 143rd Pennsylvania Infantry Monument (MN038-E) has two flanking markers, and this position marker along with another two position markers. This position marker is rather large and involved compared to the other ones at Gettysburg. One might wonder if this had its own listing but it does not. The monuments were all dedicated on September 11, 1889 by the Commonwealth of Pennsylvania. The markers are composed of granite. The monument is three-tiered. The base, smooth on top and rough on its sides is approximately 3 feet wide, 2 feet deep and a foot high. The next level sits in the middle of the base, exposing the edges. This is approximately 2 feet wide, 1.5 feet deep and 3/4 feet high. The third tier is the actual monument. It is about 2.5 feet high X 3 feet wide by a foot or so deep. Additional details from the nomination form concerning the flank monuments may be found below in red. There are full inscriptions on the front and reverse sides, all of which reads:
(Front):143rd Penna. Infantry
2nd Brig. 3rd Div. 1st Corps
Held this position July 2nd and 3rd 1863
and assisted in the repulse of the enemy on the 3rd.
Monument erected on 1st days field
near Reynolds Grove where the regiment lost 145 killed
and wounded and 91 missing out of 465 present for duty.
Losses here 16 killed and wounded.
Army of the Potomac
(Back):Engagements
Chancellorsville. Gettysburg.
Wilderness. Laurel Hill.
Spotsylvania. North Anna.
Bethesda Church. Cold Harbor.
Petersburg. Weldon R.R.
Vaughn Road. Hatchers Run.
Mustered in Luzerne Co. Aug. 26, 1862.
Mustered Out. June 12, 1865.
The 143rd Pennsylvania Infantry & the position monument are a contributing features to the Gettysburg National Military Park Historic District which is nationally significant under NR Criteria A, B, C & D. Areas of Significance: Military, Politics/Government, Landscape Architecture, Conservation, Archeology-Historic. Period of Significance: 1863-1938. The original National Register Nomination was approved by the Keeper March 19, 1975. An update to this nomination was approved by the Keeper on January 23, 2004. The monuments are collectively identified as structure number MN249-C.
From the Nomination Form:
Marks position of 143rd Pennsylvania on afternoon of July 1, 1863. 1 of 110 mns in Park to PA units at Gettysburg. Located on S side Chambersburg Pike, W of Reynolds Av. Pos. marker marks regiment on July 2 & 3: Located E side Hancock Av. w/its flank markers.
Short Physical Description:
Mn, 2 flank markers & 1 position marker w/ 2 flank markers. Rough & smooth monolith w/ relief of soldier, 2'9"x1'6", 5' high. Inscription, corps insignia & state seal on N. Flank markers apex topped, 6"x6"x1'6". Position marker, 4'x2'7", 4'9" high.
Long Physical Description
A monument that has two flanking markers and one position marker with two flanking markers. Monument is a rough and smooth granite monolith with relief of a soldier five foot high. Inscription, corps insignia, and state seal are on the north side. Flanking markers are apex topped, 6x6 inches. They are located on the south side of the Chambersburg Pike west of Reynolds Avenue. Position marker is 4x4.7 foot and 4.9 foot high. It, with the two flanking markers, is located on the east side of Hancock Avenue.
My Sources
1.
NRHP Narrative
2.
Stone Sentinels
4.
Virtual Gettysburg
5.
Draw the Sword
6.
Historical Marker Database