The 19th Massachusetts Infantry Monument served as a member of Hall’s Brigade in Gibbon’s Division of the Second Corps, Army of the Potomac, a Fighting 300 Regiment. The 19th into Federal service on August 28, 1861. All totaled, the 19th Massachusetts Infantry Regiment lost 14 officers and 147 enlisted men killed or mortally wounded and 133 enlisted men to disease during the Civil War. The 19th Massachusetts Infantry was commanded by Colonel Arthur F. Devereux (April 27, 1838 – February 13, 1906). He was notable for his expertise and proficiency in the instruction of military drill. During the Battle of Gettysburg, the 19th Massachusetts, under his command, played an important role in filling a breach in the Union lines during Pickett's Charge. After his active service had concluded, Devereux was awarded the honorary rank of brevet brigadier general, United States Volunteers, by appointment of President Andrew Johnson on February 21, 1866 to rank from March 13, 1865, and confirmation by the U.S. Senate on April 10, 1866. Arthur Devereux died on February 13, 1906 and was laid to rest in Cincinnati. The regiment under Colonel Devereaux brought 231 men to the field, with 9 men killed, 61 wounded and 7 who went missing.
The 19th Massachusetts Infantry Monument is located on the right or east side of 
Hancock Avenue (RD310) if traveling north along the road at an area called The Angle. This monument is 135 feet northeast of the United States Regulars Monument (MN235). On this side of the road and across the road, there are about 1080 feet of green fields with a line of monumentation spread across it representing the line of union regiments who defended Cemetery Ridge at The Angle against Longstreet's assault also referred to as Pickett's Charge on July 3, 1863, the final day of the Great Battle. 
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 4:15 P.M. I was at an elevation of 581 feet, ASL. I used a Canon PowerShot 14.1 Megapixel, SX210 IS digital camera for the photos.
The Draw the Sword site helped out by the NPS narrative and the SIRIS site offers the following description: Slant-faced marker includes relief images of a knapsack and a bugle. An infantry cartridge box rests on top. The front inscription block and the knapsack are polished. Monument is a chamfered granite shaft with a flat face topped with a cartridge box and set on a 4×5 foot rough cut base with tooled edges. The shaft has an incised inscription in polished stone and the angle has a detail of a knapsack and bugle. Overall height is seven feet. Flanking markers are 1.6x.8 foot with a polished face and gable design. Monument indicates the position held by the 19th Massachusetts Infantry on July 3, 1863 prior to and during Longstreet’s assault before rushing toward the Angle to assist the Philadelphia Brigade.
The monument was dedicated October 1, 1891 by the Commonwealth of Massachusetts. The monument is composed of Westerly granite and has the following dimensions: The sculpture is 7 feet high and the base is approximately 4 feet in height and five feet in width. The monument was fabricated by the Smith Granite Company out of Westerly, Rhode Island. The fact Westerly granite was used for the monument and it was manufactured by the Smith Granite Company is no coincidence. In 1845 Orlando Smith discovered a granite outcrop on the property owned by Joshua Babcock in Westerly, Rhode Island, and a year later purchased the site from him. He established a granite quarry shortly there after and by the 1850s was cutting granite monuments. In 1887 the Smith Granite Company was incorporated, with family members holding all the stock.. There is a brief inscription on the front which reads:
The 19th Reg't Mass. Vol. Infty
of the
3rd Brigade - 2nd Division - 2nd Army Corps
stood here
on the afternoon of July 3rd 1863
The 19th Massachusetts Infantry Monument is a contributing feature 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 monument is identified as structure number MN245-B.
From the Nomination Form:
1 of 25 Massachusetts Mn. Indicates position held by 19TH Mass. July 3, 1863 before & during Longstreet's Assualt. Located E side Hancock Ave, near Copse of Trees. LF&RF markers 66' & 67' N-S of Mn, respectively.
Short Physical Description:
Mn & 2 flank markers. Rough cut base 4'x5' w/tooled edges. Chamfered shaft w/flat face & incised inscription in polished stone and angle has detail of knapsack & bugle. Sculpt. cartridge box rests at top. All 7'H. LF&RF 1'6"x8"x2'2", polished face, gable design.
Long Physical Description:
Monument that has two flanking markers. Monument is a chamfered granite shaft with a flat face topped with a cartridge box and set on a 4x5 foot rough cut base with tooled edges. The shaft has an incised inscription in polished stone and the angle has a detail of a knapsack and bugle. Overall height is seven feet. Flanking markers are 1.6x.8 foot with a polished face and gable design. Located on the east side of Hancock Avenue, near the Copse of Trees.
My Sources
1.
NRHP Nomination Form
2.
SIRIS
3.
Stone Sentinels
4.
Virtual Gettysburg
5.
Draw the Sword
6.
Historical Marker Database
7.
Wikipedia