Many American cities were dubbed a “Magic City” in the 1800s because of rapid growth, Cheyenne, Wyoming was called the “Magic City” since 1867.
 
South Omaha, Nebraska was called the ‘Magic City” in April 1888. An article in the Magazine of Western History in April 1889 about South Omaha was titled “The Magic City.”
 
Omaha has been nicknamed the “Big O” since the 1970s.
 
   
Wikipedia: Omaha, Nebraska
Omaha (/ˈoʊməhɑː/ oh-mə-hah) is the largest city in the state of Nebraska and the county seat of Douglas County. Omaha is located in the Midwestern United States on the Missouri River, about 10 miles (15 km) north of the mouth of the Platte River. Omaha is the anchor of the Omaha-Council Bluffs metropolitan area, which includes Council Bluffs, Iowa, across the Missouri River from Omaha. According to the 2010 census, Omaha’s population was 408,958, making it the nation’s 43rd-largest city. According to the 2014 Population Estimates, Omaha’s population was 446,599. Including its suburbs, Omaha formed the 60th-largest metropolitan area in the United States in 2013, with an estimated population of 895,151 residing in eight counties. The Omaha-Council Bluffs-Fremont, Nebraska-IA Combined Statistical Area is 931,667, according to the U.S. Census Bureau’s 2013 estimate. There are nearly 1.3 million residents within the Greater Omaha area, comprising a 50-mile (80 km) radius of Downtown Omaha, the city’s center.
     
Nebraska Newspapers
20 April 1888, Omaha (NE) Daily Bee, pg 6, col. 3:
SOUTH OMAHA NEWS.
A Magic City.
Marvelous as was the growth of South Omaha during 1887, the summer of 1888 bids fair to surpass it, and to win for it the title of the Magic city.
 
Nebraska Newspapers
10 May 1888, Omaha (NE) Daily Bee, pg. 3, col. 5:
SOUTH OMAHA NEWS.
(...)
In the mean time the money will be spent in South Omaha and the magic city will bloom.
 
Google Books
April 1889, Magazine of Western History, pg. 681:
“THE MAGIC CITY.”
(South Omaha, Nebraska.—ed.)
 
Google Books
Omaha and South Omaha Illustrated
Omaha, NE: D. C. Dunbar & Co.
1890            
Pg. 46:
SOUTH OMAHA
No appellation was ever more appropriate than that of ” Magic City ” given to South Omaha. Other cities have sprung up as if by magic, but this one seemed to come full equipped to do a gigantic business from the first.
 
Google Books
Anecdotes of Omaha
By Mrs. Mary B. Newton
Omaha, NE: Festner Printing Company
1891
Pg. 127:
Six years ago the city of South Omaha, the Magic City, was only a farm with one or two houses, where now is a population of ten thousand and some of the finest packing houses in America.
 
Google Books
Pen and Sunlight Sketches of Omaha and Environs
Chicago, IL: Phoenix Publishing Company
1892
Pg. 74:
It (South Omaha—ed.) is well termed “The Magic City,” for none other has, in the like time, become so fully equipped to do a gigantic business as this city.
 
OCLC WorldCat record
The magic city hoof and horn
Publisher: South Omaha, Neb. : Allerby Print. Co., 1898-
Edition/Format:   Newspaper : Microfilm : Master microform : English
 
OCLC WorldCat record
South Omaha and South Omahans : being a compilation of facts and faces that have had to do with the general progress of the magic city, and a little “squint” into the future. Published in celebration of the close of a quarter of a century of history of the most interesting and the most marvelously grown city in the mid-west
Author: A J W Lloyd; D A Pierce
Publisher: South Omaha, Neb. : Diers-Landis Co., 1910.
Edition/Format:   Print book : Biography : English
 
OCLC WorldCat record
Tom Hoctor in “the Magic City” : the ascendancy and eclipse of South Omaha sovereignty
Author: Emmett Charles Hoctor
Publisher: [La Platte, Neb.] : [E.C. Hoctor], [1981?]
Edition/Format:   Print book : English
 
Google Books
Omaha’s Historic Houses of Worship
By Eileen Wirth PhD and Carol McCabe
Charleston, SC: Arcadia Publishing
2014
Pg. 65:
Residents called South Omaha “Magic City” because of its robust economy, although its odor seemed scarcely magic to others.