The ideals expressed in the speech also weren't necessarily a reflection of reality. Only a few years after the war a separate cemetery for black Civil War veterans was created in Gettysburg because they were "denied burial in the National Cemetery because of segregation policies," according to a historical marker placed in 2003.
The free Dedication Day event is held annually at Soldiers' National Cemetery. Last year's commemoration drew some 9,000 people.
President Barack Obama declined an invitation, and parks officials say Rutherford B. Hayes is the last sitting president to attend a Nov. 19 event in Gettysburg.
There are several related events at the park this week, including the "Gettysburg Address Gallery" at the park museum and visitor center. The exhibit includes pages with signatures of individuals who attended the 1863 Dedication Ceremony in Gettysburg and a letter and signed pardon from Lincoln.
The annual Remembrance Day Parade in Gettysburg will be held Saturday, featuring Union and Confederate re-enactors who will lay wreaths at the portions of the battlefield their units defended.
An estimated 235,000 people came to Gettysburg this year on or around the battle's anniversary in early July.
The National Park Service is streaming Tuesday's ceremony live to 90,000 colleges, schools, libraries and museums nationwide.
Scolforo reported from Harrisburg.