The name “Emerald City” was popularized in the Oz books by L. Frank Baum (1856-1919) and the movie The Wizard of Oz (1939). The city of Eugene, Oregon, has called itself the “Emerald City” since at least 1959.
 
The city of Seattle, Washington, held a nickname contest in 1981 and chose the same “Emerald City” nickname for its winning entry.
   
 
Wikipedia: Eugene, Oregon
Eugene ( /juːˈdʒiːn/) is a major city of the Pacific Northwest located in the state of Oregon. It is the second largest city in the U.S. state of Oregon and the county seat of Lane County. It is located at the south end of the Willamette Valley, near the confluence of the McKenzie and Willamette rivers, about 50 miles (80 km) east of the Oregon Coast.
 
As of the 2010 U.S. Census, Eugene has a population of 156,185, and Lane County (co-located with the Eugene-Springfield Metropolitan Statistical Area) (MSA) has a population of 351,715. While Eugene has long been the second largest city in Oregon, it was briefly surpassed by Salem between 2005 and 2007. The Eugene-Springfield, Oregon MSA is the 144th largest metropolitan statistical area of the U.S, and the third largest in the state, behind the Portland Metropolitan Area and the Salem Metropolitan Area.
 
Eugene is home to the University of Oregon. The city is also noted for its natural beauty, recreational opportunities (especially bicycling, running/jogging, rafting, kayaking), focus on the arts, activist political leanings, and residents with “alternative” lifestyles. Eugene’s slogan is “A Great City for the Arts and Outdoors.” It is also referred to as the “Emerald City”, and as “Track Town, USA.” The Nike corporation had its beginnings in Eugene.
 
Wikipedia: Emerald City (disambiguation)
The Emerald City is the capital city of the Land of Oz in the Oz books and the 1939 film The Wizard of Oz.

Emerald City may also refer to:
 
. The Emerald City of Oz, the sixth book in the Oz series, by L. Frank Baum
(...)
. The nickname of:
.. Seattle, Washington, United States
.. Sydney, New South Wales, Australia
.. Muntinlupa, Philippines
.. Eugene, Oregon, United States
.. Greenwood, South Carolina, United States
.. Green Zone, Baghdad, Iraq
.. Oracle World Headquarters, Redwood Shores, CA
.. Syracuse, New York, United States
.. Wichita, Kansas, United States
 
Google News Archive
14 January 1959, The Register-Guard (Eugene, OR), pg. 8A, col. 3:
This would be proper, although the general public reaction is that South Eugene High should remain on the “outside” for a full year as punishment for the humiliating way visiting athletes and students—and fans—are treated when visiting at the Emerald City school.
 
1 March 1960, The Oregonian (Portland, OR), ‘Boise Entry Wins Title,” pg. 2, col. 1:
In seventh place was the Emerald City Four of Eugene and, in the cellar position, were the Rain-Aires of Bellevue, Wash.
 
29 November 1981, Seattle (WA) Times, “Murray hatchet job rates with G. Washington’s” by Hy Zimmerman, pg. B6, col. 4:
There, our own provincialism is showing: And why not, domiciled in a place like Seattle? We deplored that contest which named our town the Emerald City, a nickname already enjoyed by Eugene, Ore.
 
Google News Archive
13 December 1984, The Register-Guard (Eugene, OR), “The king no longer?” by Bud Withers, pg. 1C, col. 1:
AS CITIES GO, EUGENE has lately come in for its share of lumps. THe lumber industry sagged, new business looked askance at us. The Hult Center, once a monument to our cosmopolitan vision, is embroiled in controversy. We shrugged as Seattle went searching for a nickname for itself and chose the Emerald City.
 
Google News Archive
1 September 1988, Lewiston (ID) Morning Tribune, “Living the Good Life…the Dead Live,” pg. 1D, col. 1:
And when it (The Grateful Dead—ed.) goes to the emerald city of Eugene it creates music right before your eyes and makes new sounds right in your ears.