People from Wisconsin are nicknamed “Badgers.” The University of Wisconsin officially adopted the “Badgers” nickname in 1889.
 
“A keen-eyed leather-belted “badger” from the mines of Ouisconsin” was written in a diary entry on December 26, 1933, by New York City-born author, poet and editor Charles Fenno Hoffman (1806-1884). The miners of Wisconsin were said to resemble badgers, and the term was applied to non-miners as well.
 
     
Wikipedia: Wisconsin Badgers
The Wisconsin Badgers are the athletic teams representing the University of Wisconsin–Madison (University of Wisconsin). They compete as a member of the National Collegiate Athletic Association (NCAA) Division I level (Football Bowl Subdivision (FBS) sub-level), primarily competing in the Big Ten Conference for all sports since the 1896-97 season.
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Team name origin
Wisconsin was dubbed the “Badger State” because of the lead miners who first settled there in the 1820s and 1830s. Without shelter in the winter, they had to “live like badgers” in tunnels burrowed into hillsides.
 
The badger mascot was adopted by the University of Wisconsin in 1889. His name, “Buckingham U. Badger”, a.k.a. “Bucky Badger,” was chosen in a contest in 1949. The emblem, a scowling, strutting badger wearing a cardinal-and-white striped sweater, was designed by Art Evans in 1940 and updated in 2003. A live badger from Eau Claire was used at the first few football games that year, but proved to be too fierce to be controlled and was retired to the nearby Henry Vilas Zoo. For a time, the school replaced the live badger with a live raccoon named “Regdab” (“badger” backwards). In 2006, Bucky Badger was inducted as a charter member of the Mascot Hall of Fame’s College Division, joining YoUDee from Delaware and Aubie from Auburn.
 
(Oxford English Dictionary)
badger, n.
a. Esp. in Wisconsin: a lead miner, spec. one who lives in a dugout close to the diggings. Now hist. and rare.
1833   C. F. Hoffman Let. 26 Dec. in Winter in West (1835) I. 207   A keen eyed, leather-belted ‘badger’ from the mines of Ouisconsin.
1843   Madison (Wisconsin) City Express (Electronic text) 1 June   What had the poor Badgers done to provoke the wrath of heaven? Why has John Flanagan been put astride of the mining interests, with Cunningham upon the crupper, to ride it into the ground?
1844   G. C. Hebbe & J. MacKay tr. ‘C. Sealsfield’ Life in New World ii. i. 61/1   It seems as if all the western states and territories had sent representatives on board of our steamer. Suckers from Illinois, and Badgers from the lead mines of Missouri..stood in the most lovely confusion before us.
1937   G. E. Shankle Amer. Nicknames 588   Badger..was applied to the early lead miners, who on first coming to a new location dug in the side of a hill and lived under ground much as the badger digs in his burrow.
b. A native or inhabitant of Wisconsin.
1844   Knickerbocker Sept. 286   The inhabitants [of Wisconsin] are called ‘badgers’.
 
Google Books (The same passage as below, in the American Railroad Journal, March 1, 1834. It was written by Charles Fenno Hoffman and published in book form in 1835.—ed.)
22 February 1834, New-York (NY) American, “Review of the Week,” pg. 2, col. 1:
There was a long-haired “hooshier” from Indiana, a couple of smart-looking “suckers” from the southern part of Illinois, a keen-eyed leather-belted “badger” from the mines of Ouisconsin, and a sturdy yeomanlike fellow, whose white capote, Indian mockasons, and red sash proclaimed, while he boasted a three years residence, the genuine wolverine, or naturalized Michiganian. Could one refuse a drink with such a company? The spokesman was evidently a “red-horse” from Kentucky, and nothing was wanting but a “buckeye” from Ohio, to render the assemblage as complete as it was select.
 
Google Books
A Winter in the West
Volume 1
By a New Yorker (Charles Fenno Hoffman.—ed.)
New York, NY: Harper & Brothers
1835
Prairie Ronde, Kalamazoo Co., M.T., Dec. 26. (1833—ed.)
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There was a long-haired “hooshier” from Indiana, a couple of smart-looking “suckers” from the southern part of Illinois, a keen-eyed leather-belted “badger” from the mines of Ouisconsin, and a sturdy yeomanlike fellow, whose white capote, Indian mockasons, and red sash proclaimed, while he boasted a three years residence, the genuine wolverine, or naturalized Michiganian. Could one refuse a drink with such a company? The spokesman was evidently a “red-horse” from Kentucky, and nothing was wanting but a “buckeye” from Ohio, to render the assemblage as complete as it was select.
 
Google Books
Ralph Doughby’s Esq.
Volume 3
By Charles Sealsfield
Zürich: Orell, Fußli & Co.
1835
Pp. 12:
Suckers von Illinois, und Badgers von den Bleiminen Missouris, und Wolverines von Michigan, und Buckeyes von Ohio, untermengt mit Red-horses vom alten Kentucky, ...
   
20 July 1836, Du Buque (IA) Visitor, pg. 42, col. 2:
By J. Catlin.—The Badgers of Wisconsin.—Their energy and perseverance is a sure guarantee of future prosperity.
 
Newspapers.com
21 July 1836, Milwaukee (WI) Advertiser, pg. 5, col. 4:
“The HAWK-EYES.”
MR. EDITOR:
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“A HAWK-EYE.”
1st. Resolved,—That having been endowed with the right of self-government, and thereby absolved from all political dependence on Michigan, we renounce all right and claim to the appellation “Wolvereens.”
2nd. Resolved,—That we are willing and desirous hereafter, to be known and distinguished by the style, name and title of “HAWK-EYES”—a term more harmonious to the ear, more brief and convenient, than that of Wisconsians, or Wisconsonians, or Wisconsinites.
Milwaukee, July 10, 1836.
[It is easily to be perceived that our friend “A Hawk Eye” has not long been a resident of Wisconsin,—if he had been, he would know that we have long possessed the honorable cognomen of Badgers. The inhabitants of the western part of Wisconsin, are or were, when the name was given engaged in digging Led Ore—hence from the habits of that animal, of boroughing in the earth during the day, we are called Badgers. Therefore, being opposed to all changes or innovations in old or long established names or customs, and having a great aversion to all long names, whether belonging to men in their individual or public capacity, we wish to retain our old name, which has obtained the sanction of time.]
     
Newspapers.com
17 December 1836, Milwaukee (WI) Advertiser, pg. 2, col. 1:
For the Milwaukee Advertiser.,
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Who, pray, is Mr. Sweet? He must have been born and raised in the territory. he must be a Badger by nature.
 
Google Books
September 1844, The Knickerbocker: Or, New-York Monthly Magazine, “Gossip with Readers and Correspondents,” pg. 286:
OUR friend the Milwaukie Badger tempts us sorely. (...) Dear and time-honored KNICK: do you know that there is such a country as Wisconsin? that it is beyond Lake Michigan? that on the western shore of that lake is Milwaukie, the most beautiful village this side of sun-down? that the inhabitants are called ‘badgers’? and that the forests they clear and the houses they rear fully attest their right to that title?
       
OCLC WorldCat record
The home of the badgers, or, A sketch of the early history of Wisconsin : with a series of familiar letters and remarks on territorial character and characteristics, etc.
Author: Josiah Bushnell Grinnell
Publisher: Milwaukee [Wis.] : Wilshire & Co., 1845
Edition/Format:   eBook : Document : English
 
Google Books
April 1845, Cincinnati Miscellany (Cincinnati, OH), pg. 240, col. 1:
Ohio,          Buckeyes.
Indiana,        Hoosiers.
Illinois,        Suckers.
Missouri,        Pewks.
Mississippi,      Tadpoles
Arkansas,      Gophers.
Michigan,        Wolverines.
Florida,          Fly up the Creeks.
Wisconsin,      Badgers.
Iowa,          Hawkeyes.
N. W. Territory,  Prairie Dogs.
Oregon,        Hard Cases.
 
Chronicling America
23 August 1845, Ripley (MS) Advertiser, pg. 1, cols. 4-5:
NATIONAL NICKNAMES.—It will be seen by the following from an exchange paper that the people of every state have nicknames, and some very curious and ludicrous ones:
 
The inhabitants of Maine, are called Foxes; New Hampshire, Granite Boys; Massachusetts, Bay Staters; Vermont, Green Mountain Boys; Rhode Island, Gun Flints; Connecticut, Wooden Nutmegs; New York, Knickerbockers; New Jersey, Clamcatchers; Pennsylvania, Leatherheads; Delaware, Muskrats; Maryland, Craw-Thumpers; Virginia, Beagles; North Carolina, Weasels; Georgia, Buzzards; Louisiana, Creowls; Alabama, Lizzards; Kentucky, Corn crackers; Tennessee, Cottonmanics; Ohio, Buckeyes; Indiana, Hoosiers; Illinois, Suckers; Missouri, Pewks; Mississippi, Tadpoles; Arkansas, Gophers; Michigan, Wolverines; Florida, Fly-up-the-Creeks; Wisconsin, Badgers; Iowa, Hawkeyes; N. W. Territory, Prairie Dogs; Oregon, Hard Cases.
 
Chronicling America
4 July 1860, The Spirit of Democracy (Woodsfield, OH), “National Nicknames,” pg. 1, col. 7:
The inhabitants of Maine are called Foxes; New Hampshire, Granite Boys; Massachusetts, Bay Staters; Vermont, Green Mountain Boys; Rhode Island, Gun Flints; Connecticut, Wooden Nutmegs; New York, Knickerbockers; New Jersey, Clam Catchers; Pennsylvania, Leather Heads; Delaware, Muskrats; Maryland, Claw Thumpers; Virginia, Beagles; North Carolina, Tar Boilers; South Carolina, Weasels; Georgia, Buzzards; Louisiana, Creowls; Alabama, Lizards; Kentucky, Corn Crackers; Ohio, Buckeyes; Michigan, Wolverines; Indiana, Hoosiers; illinois, Suckers; Missouri, Pukes: Mississippi, Tad-Poles; Florida, Fly up the Creeks; Wisconsin, Badgers; Iowa, Hawkeyes; Oregon, Hard Cases.
 
OCLC WorldCat record
Badger state soldiers, “Motto,” We live for the union. We die for the union. We will uphold the union. Milwaukee
Publisher: [New York] : Charles Magnus, 12 Frankfort St., N.Y., [between 1861 and 1865]
Series: Archive of Americana.; American broadsides and ephemera., Series 1 ;, no. 25318.
Edition/Format:   Print book : Document   Computer File : English
 
Google Books
June 1865, The Wisconsin Journal of Education, pg. 328:
The following are the “nicknames” of the native inhabitants of the different States:
... Wisconsin, Badgers; ...
 
1 December 1865, The Rescue (Sacramento, CA), “National Nicknames,” pg. 3, col. 3:
... Wisconsin, Badgers; ...
 
Google Books
Annual Statistician—1876
Compiled by John P. Mains
San Francisco, CA: L. P. McCarty, Publisher
1876
Pg. 90:
NICKNAMES OF STATES AND THEIR INHABITANTS.
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WISCONSIN—The Badger State. Badgers.
 
OCLC WorldCat record
The badger.
Author: University of Wisconsin.
Publisher: Madison, Wis. : Junior Class of the University of Wisconsin, 1888-1970
Edition/Format:   Journal, magazine : English
 
Google Books
The Story of Wisconsin
By Reuben Gold Thwaites
Boston, MA: D. Lothrop Company
1890
Pg. 205:
In early lead-mining days, the miners from Southern Illinois and further south returned home every winter and came back to the diggings in the spring, thus imitating the migrations of the fish popularly called the “sucker,” in the Rock, Illinois and other south-flowing rivers of the region. For this reason, the south-winterers were jocosely called “Suckers,” and Illinois became “The Sucker State.” On the other hand, miners from the Eastern States were unable to return home every winter and at first lived in rude dug-outs—burrowing into the hillsides after the fashion of the badger (Texidea americana). These men were the first permanent settlers in the mines north of the Illinois line, and Wisconsin thus became dubbed “The Badger State.” Contrary to general belief, the badger itself is not frequently found in Wisconsin.
 
Google Books
U. S.
An Index to the United States of America
Compiled by Malcolm Townsend
Boston, MA: D. Lothrop Company
1890
Pg. 74:
NICKNAMES OF THE STATES.
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Wisconsin…Badger...From the representation of a badger on the State Coat of Arms—originally applied owing to the great numbers of badgers formerly in the State.
 
Google Books
Universal Dictionary of the English Language
Edited by Robert Hunter and Charles Morris
New York, NY: Peter Fenelon Collier, Publisher
1898
Pg. 5344:
Wisconsin. The Badger State (the State coat-of-arms bears a badger).
 
Our Ontario
31 December 1936, The Canadian Champion (Milton, ON), pg. 1, col. 3:
“Badger State” Nickname
The term “Badger State” was applied to the early lead miners who on first coming to a new location dug in the side of a hill and lived underground much as the badger digs in his burrow. The lead mines were located near the corner of the state where Wisconsin, Illinois and Iowa meet. At first the term was applied in derision to the occupants of these temporary subterranean residences, then to all the inhabitants of the mining region, then to all the people of the state.
 
OCLC WorldCat record
Wisconsin : a guide to the Badger State
Author: Writers’ Program of the Work Projects Administration in the State of Wisconsin.
Publisher: New York : Duell, Sloan and Pearce, ©1941.
Series: American guide series.
Edition/Format:   Print book : English
 
Google News Archive
3 March 1957, Milwaukee (WI) Journal, “What’s in Big Ten Nickname?” by Cleon Walfoort, pt. 3, pg. 4, col. 6:
That leaves only Wisconsin’s own Badgers. Any true state resident who doesn’t know that it originally referred to the miners who dug into the ground, like badgers, rather than to the animal itself should be sent to Madison for graduate work.
 
Wisconsin Historical Society
Wisconsin Magazine of History: Volume 76, number 2, winter, 1992-1993
Pg. 121:
From Where Come the Badgers?
By Karol D. Bicha