The city of Minneapolis (MN) is on the west side of the Mississippi River, and St. Paul (MN) is on the east side. It’s often said of these Twin Cities that Minneapolis is the “First City of the West” and St. Paul is the “Last City of the East.”
 
“The Northwest” was printed in the Baltimore (MD) Sun on August 27, 1898:
 
“The Northwest begins at St. Paul and Minneapolis. These two cities, whose centres are not more than ten or twelve miles apart, lie the first on the east and the second on the west bank of the Mississippi river. The East ends at St. Paul; the West begins at Minneapolis. When one crosses the Father of Waters and enters upon the great expanse of Northern Minnesota and North Dakota he feels as if he had begun the final step in the journey to the ‘Far West.’”
   
“There is a much-quoted pronouncement to the effect that St. Paul is the last city of the East, Minneapolis the first city of the West” was cited in print in 1960.
 
“Where the West begins” (a slogan of Fort Worth, Texas) was cited in 1911. “Where the East ends” (a related slogan of Dallas, Texas) has been cited in print since at least 1947.
 
 
Wikipedia: Minneapolis-Saint Paul
Minneapolis–Saint Paul is a major metropolitan area built around the Mississippi, Minnesota and St. Croix rivers. The area is commonly known as the Twin Cities for its two largest cities, Minneapolis, the city with the largest population in Minnesota, and Saint Paul, the state capital. It is a classic example of twin cities in the sense of geographical proximity. Together the two cities anchor the second-largest economic center in the Midwest, behind Chicago.
 
Wikipedia: Minneapolis
Minneapolis (/ˌmɪniˈæpəlɪs/) is the county seat of Hennepin County, and larger of the Twin Cities, the 14th-largest metropolitan area in the United States, containing approximately 3.8 million residents. As of 2016, Minneapolis is the largest city in the state of Minnesota and 46th-largest in the United States with 407,207 residents. Minneapolis and Saint Paul anchor the second-largest economic center in the Midwest, behind Chicago.
 
Minneapolis lies on both banks of the Mississippi River, just north of the river’s confluence with the Minnesota River, and adjoins Saint Paul, the state’s capital.
 
Wikipedia: Saint Paul, Minnesota
Saint Paul (/ˌseɪnt ˈpɔːl/; abbreviated St. Paul) is the capital and second-most populous city of the U.S. state of Minnesota. As of 2014, the city’s estimated population was 297,640. Saint Paul is the county seat of Ramsey County, the smallest and most densely populated county in Minnesota. The city lies mostly on the east bank of the Mississippi River in the area surrounding its point of confluence with the Minnesota River, and adjoins Minneapolis, the state’s largest city. Known as the “Twin Cities”, the two form the core of Minneapolis–Saint Paul, the 16th-largest metropolitan area in the United States, with about 3.5 million residents.
   
27 August 1898, The Sun (Baltimore, MD), “The Northwest: A Baltimorean’s Interesting Description Of A Trip Across The Continent,” pg. 6, col. 3:
The Northwest—The Twin Cities.
The Northwest begins at St. Paul and Minneapolis. These two cities, whose centres are not more than ten or twelve miles apart, lie the first on the east and the second on the west bank of the Mississippi river. The East ends at St. Paul; the West begins at Minneapolis. When one crosses the Father of Waters and enters upon the great expanse of Northern Minnesota and North Dakota he feels as if he had begun the final step in the journey to the “Far West.”
(...)
C. HERBERT RICHARDSON.
 
Google Books
Newsweek
Volume 45
1955
Pg. 102:
Somebody said that the East ends in St. Paul and the West begins in Minneapolis.
   
Google Books
American Panorama: West of the Mississippi
Holiday, periodical
Doubleday, 1960
Pg. 367:
There is a much-quoted pronouncement to the effect that St. Paul is the last city of the East, Minneapolis the first city of the West.
 
Google News Archive
16 October 1980, Pittsburgh (PA) Press, “St. Paul: Hearty Helping Of Hospitality” by Marilyn McDevitt Rubin, pg. B-5, col. 1:
St. Paul is affectionately considered the last city of the East while Minneapolis is known as the first city of the West.
   
2 November 1986, Minneapolis (MN) Star Tribune, “As Minnesota’s symbols have changed, so has America; Humphrey and Dylan once symbolized the Midwest. Now Keillor and Prince do” by Carol Byrne, pg. 65M:
St. Paul is the last city of the East and Minneapolis the first city of the West. We are farm country, but we are the urban center for the prairie land from here to the West Coast. We have Garrison Keillor for the older people and Prince for the young.
 
East, West, urban, rural, young, old, black, white and even androgynous. Minnesota is all of these things, and so is America.
 
28 December 1986, Minneapolis (MN) Star and Tribune, “As construction slows, Minneapolis faces midlife crisis” by Linda Mack, pg. 2G:
It has often been said that St. Paul is the last city of the East and Minneapolis the first city of the West.
   
Google Books
Minnesota
By Martin Hintz
New York, NY: Children’s Press
2000
Pg. 71:
Because the Mississippi River snakes between the two cities, Minneapolis has been called “the first city of the West” and St. Paul, the state capital, “the last city in the East.”
 
March 2011, Minnesota Monthly, “Q & A: City Stories” by Tim Gihring, pg. 22:
Q: Has there always been a rivalry between the cities?
 
kk: There’s truth behind the notion that St. Paul is the last city of the East and Minneapolis the first city of the West. St. Paul has that traditional, blue-collar feel, and Minneapolis has some elbow room—along with the folly of youth.
   
Google Books
Wish You Were Eyre
By Heather Vogel Frederick
New York, NY: Simon & Schuster
2013
Pg. 261:
“In the nineteenth century, St. Paul was known as ‘the last city of the East,’ while Minneapolis was ‘the first city of the West.’”