Pennsylvania: Keystone State (nickname)

Pennsylvania has been called the “Keystone State” for several reasons. A keystone is a wedge-shaped stone that holds an arch in place. Pennsylvania was located in the center of the 13 original states of the United States, and also was where the Declaration of Independence and the Constitution were signed.
 
The website Founders Online shows citations of “key-stone” and “keystone,” but no citation specifically refers to Pennsylvania. “The oath prescribed by the Constitution is the key-stone of the Federal Arch” was cited in a 1795 newspaper. “The state of New-York. May she be more and more distinguished, as a principal Pillar of the Federal Arch” was cited in a 1797 newspaper.
 
“This key-stone state”—meaning Pennsylvania—was cited in a March 1804 newspaper. A toast was made is October 1804:
 
“The commonwealth of Pennsylvania—Nature’s key stone in the arch of the union, may she continue the key stone in the arch of principle.”
 
“Key-stone State” began to be popularly used in 1831 and “old Key-stone” in 1832.
 
 
VisitPA.com (official tourism website)
The Keystone State
A “keystone” is a central, wedge-shaped stone which holds all the other stones of a structure in place to form an arch. In early America, Pennsylvania played a vital geographic and strategic role in holding together the states of the newly formed Union. Today, Pennsylvania continues to be of key importance to the social, economic and political development of the United States.
   
Wikipedia: Keystone
A keystone is the wedge-shaped stone piece at the apex of a masonry vault or arch, which is the final piece placed during construction and locks all the stones into position, allowing the arch to bear weight. Although a masonry arch or vault cannot be self-supporting until the keystone is placed, the keystone experiences the least stress of any of the voussoirs, due to its position at the apex. Old keystones can decay due to vibration, a condition known as bald arch.
 
(Oxford English Dictionary)
keystone, n.1 and adj.
U.S. More fully old Keystone. (A nickname for) the state of Pennsylvania; = Keystone State n. at Compounds. Now rare.
With quot. 1803   cf. sense A. 1b.
[1803   Addr. by Democratic Comm. in H. M. Jenkins Pennsylvania (1903) II. xii. 316   Pennsylvania is the Keystone of the democratic arch.]
1839   Liberator 5 Apr. 54/1   Gallant Senator Buchanan, of the old Keystone.
Keystone State  n. U.S. (a nickname for) the state of Pennsylvania.
[Apparently arising partly from the address cited in quot. 1803 at sense A. 1d, and partly from Pennsylvania’s central position among the thirteen original states.]
1831 Daily National Intelligencer (Washington) 19 May 3/3   What will the ‘Key-stone’ State say to such an impudent charge brought against the whole body of her Legislature.
           
5 February 1795, The Independent Gazetteer (Philadelphia, PA), pg. 2, col. 4:
The oath prescribed by the Constitution is the key-stone of the Federal Arch.
 
5 July 1797, The Minerva, & Mercantile Evening Advertiser (New York, NY), “Chamber of Commerce,” pg. 3, col. 1:
The state of New-York. May she be more and more distinguished, as a principal Pillar of the Federal Arch.—3 cheers.
 
10 November 1801, Raleigh Register, and North-Carolina Weekly Advertiser (Raleigh, NC), “Judge Hall’s Charge,” pg. 1, col. 2:
It may well be said, tha the Judiciary is the key-stone of the federal arch.
 
11 July 1803, Gazette of the United States (Philadelphia, PA), “Hartford, July 6,” pg. 2, col. 2:
The State Governments—Each in its place a pillar to the federal arch.
 
24 March 1804, Aurora General Advertiser (Philadelphia, PA), pg. 2, col. 2:
At that crisis in the election of Thomas McKean came on, and when remember that his majority was little more than 5,000, we cannot doubt that in this great commonwealth, 2600 naturalized foreigners contributed (perhaps an indispensible) mite to save this key-stone state from a revolution against the sacred principles of 1776.
(...)
PENN.
 
29 October 1804, Aurora General Advertiser (Philadelphia, PA), “Toasts,” pg. 2, col. 1:
The commonwealth of Pennsylvania—Nature’s key stone in the arch of the union, may she continue the key stone in the arch of principle.
   
27 May 1806, Morning CHronicle (New York, NY), “Pennsylvania and New-York,” pg. 2, col. 4:
Unfortunately, however, for the chiefs of the Faction, their plans were not well laid, and Pennsylvania, which has been aptly termed the key-stone of the federal arch, received the first shock with firmness.
 
3 June 1806, Cumberland Register (Carlisle, PA), “Pennsylvania & New-York,” pg. 1, col. 1:
Unfortunately, however, for the chiefs of the Faction, their plans were not well laid, and Pennsylvania, which has been aptly termed the Key-Stone of the Federal Arch, received the first shock with firmness.
     
Google Books
Reports of Cases Adjudged in the District Court for the City and COunty of Philadelphia
By Peter Arrell Browne
Philadelphia, PA: Printed by John Binns
1813
Pg. 83 (1811):
I believe the guineas are now flying through Pennsylvania, for the election of Mr. Ross, in which if they succeed, I shall set it down as the first step towards (not a federal but) a British triumph, for I believe Pennsylvania to be the key stone of the great arch of Democracy — take away the key and the arch must fall.
 
Google Books
4 September 1824, Niles’ Weekly Register, pg. 3, col. 1:
Every body knows how Pennsylvania, (long called, in compliment to her devotion, “the key stone of the republican arch,”) stands as to the minority caucus held at Washington last winter, though she was the great patron of “regular nominations.”
 
10 February 1831, The Torch Light and Public Advertiser (Hagers-Town, MD), “Letters from Washington,” pg. 1, col. 4:
What says old Pennsylvania, the key-stone of the Federal Union?
 
19 May 1831 Daily National Intelligencer (Washington, DC), pg. 3, col. 3:
What will the “Key-stone” State say to such an impudent charge brought against the whole body of her Legislature.—Balt. Patriot.
 
22 June 1831, Baltimore (MD) Patriot & Mercantile Advertiser, pg. 2, col. 2:
SIGNS OF THE TIMES.—The Bradford (Pa.) Settler—in its sphere one of the staunchest “democratic Jackson papers” of the “key stone” State—holds the following language, in its last number.
 
25 October 1832, Democratic Free Press & Michigan Intelligencer (Detroit, MI) pg. 3, col. 3:
PRESIDENTIAL ELECTION—DIALOGUE.
Democrat.—what news from old Pennsylvania, the old Key-stone, neighbor.
 
6 March 1833, The Globe (Washington, DC), pg. 3, col. 3:
This is earnest that the old Key-stone democratic state, is inclined to sustain the military chieftain in more ways than one.
 
OCLC WorldCat record
Vested rights, and the rights of the people : highway from the west to the metropolis of the Keystone State.
Publisher: [Philadelphia, Pa.?] : [publisher not identified], [1839]
Edition/Format:   Print book : English
Database: WorldCat
Summary:
Concerns a recommendation from the Grand Jury of the Commonwealth of Pennsylvania that toll-free bridges be built across the Schuylkill River in Philadelphia, at Arch Street and elsewhere, and a recommendation from a committee of the Philadelphia City Councils that tolls be removed from the Schuylkill Permanent Bridge (at Market Street).
     
OCLC WorldCat record
The great meeting of the democracy at Reading : 30,000 freemen in council, the democracy of the old keystone aroused.
Author: Charles James Faulkner
Publisher: [Place of publication not identified] : [publisher not identified], [1852]
Edition/Format:   Print book : English
 
OCLC WorldCat record
The Keystone State in the Army. - The Keystone State is nob
Publisher: Philadelphia, Pennsylvania
Edition/Format: Article Article
Publication: THE CHRISTIAN RECORDER, (December 7, 1861)
Database: African American Newspapers
 
OCLC WorldCat record
$50 bounty Fall in Peterson Guards. : Patriots to the rescue of your good old Keystone State, and one more rally for the Constitution and our glorious Union. All young men desirous of serving the above will do well to join this company for 100 days! $16 a month, clothes & rations Come one come all and enroll in the Old Peterson Guards. Head quarters, N.W. corner of Thirteenth and Wood Streets.
Author: J W Fries; James High; J McNeight; Peterson Guards.
Publisher: [Philadelphia, Pa.] : King & Baird, 607 Sansom Street, Philadelphia., [between 1861 and 1865]
Edition/Format:   Print book : English
 
OCLC WorldCat record
Pennsylvania; a guide to the Keystone state,
Author: Writers’ Program of the Work Projects Administration in the Commonwealth of Pennsylvania.
Publisher: New York, Oxford University Press, 1940.
Series: American guide series.
Edition/Format:   Print book : English
 
OCLC WorldCat record
Key to the Keystone State, Pennsylvania
Author: League of Women Voters of Pennsylvania.
Publisher: University Park : Pennsylvania State University Press, 1989.
Edition/Format:   Print book : English : 4th ed