Minneapolis was still a hodgepodge of dirt streets and modest buildings in 1855, when a group of the city's earliest leaders affixed their signatures to a map claiming land in the burgeoning town.

The massive parchment spent the next 160 years largely hidden from public view, ultimately tucked away in a corner of Hennepin County's basement archives. That changed on Thursday night when, after a painstaking restoration, the illustrated symbol of Minneapolis' origins was unveiled at a Friends of the Hennepin County Library event downtown.

"This is one of the earliest documents of its kind that we have after the founding of the city and the county," said Ted Hathaway, manager of the library's special collections department, noting it was created only several years after the Dakota tribe relinquished land for white settlement in the 1851 Treaty of Mendota. The earliest date on the map is about a year before the Territorial Legislature ratified Minneapolis' town charter.

The map's streets look somewhat familiar as modern day downtown, but many of their names have changed — except for Hennepin, Nicollet and Washington avenues. "Cataract Street" became Portland Avenue, for example, while "Helen Street" is present-day 2nd Street. Nearby those were Ames, Rice, Pearl and Huy streets.

"Almost none of those streets were there when this map was planned," Hathaway said. "So it was a document of hope, really, it was a planning document: 'We know it's just a bunch of cows and muddy streets and a few wooden buildings, but this is what it could look like over time in the future.' "

Other maps from the period exist, but this one carries some extra weight because of the roster of signatures on its upper-right corner, written by a who's who of business and government at the time. Beside each name are lot numbers, indicating who owned which parcels.

Paper conservator Dianna Clise explained an 1855 map of Minneapolis, unveiled Thursday, that she spent four months painstakingly restoring.

The signatures include Franklin Steele, an early riverfront developer and sawmill owner who created the first bridge joining Minneapolis with what was then St. Anthony; prominent physician Alfred E. Ames, whose son would become an infamously corrupt mayor; Capt. Edward Murphy, who donated the city's first park; Judge Isaac Atwater, who authored the first extensive history of the city; and Roswell P. Russell, among the first elected county commissioners and later a member of the Legislature.

The Hennepin County recorder's office knew the framed map was collecting dust in its archives, where land records are kept in perpetuity. They decided to reach out to Hathaway's staff while trying to make space for 8,000 books moving in from another location.

Martin McCormick, Hennepin County recorder and registrar of titles, said he assumes the map hung on a wall before his office moved from City Hall to the Government Center in the 1970s.

It was in poor shape, however, mounted on a brittle cotton backing. Its restoration — which could not mask the water damage — required transferring thousands of fragments to a new, aluminum backing and making repairs with special kozo mulberry paper.

"I spent every waking minute for about four months," said Dianna Clise with the Midwest Art Conservation Center, who performed the work. "I didn't answer the phone, I didn't return e-mails. I just concentrated."

Clise said she restores about one map a year. "Given the size of it and its importance to Minneapolis history, I have not gotten anything else quite like it," Clise said.

The map is now hanging in the downtown Central Library's special collections area, which is open between 10 a.m. and 4:30 p.m. Monday through Thursday, as well as on the first and third Saturday of the month.

Eric Roper • 612-673-1732

Twitter: @StribRoper