The United States has an east coast and a west coast, but it’s sometimes said to have a “third coast.” In the 1960s and 1970s, the “third coast” was the Great Lakes region (Michigan, Illinois, Wisconsin, et al.). Chicago has used the “third coast” term, as has Nashville (to refer to music not from Hollywood or New York).
 
By the late 1970s, the Texas Gulf Coast was being called “America’s third coast.” Texas itself was soon being called the “third coast,” and several businesses in the capital city of Austin used the “third coast” name. “Third coast” has been used to describe both Austin’s music scene (since the 1980s) and Houston’s hip-hop scene (since the 1990s).
   
   
Wikipedia: Third Coast
Third Coast is an American colloquialism sometimes used to refer to the Great Lakes region. Use of the term implies that this region of the United States is distinguishable from both the East and West Coast regions. It gained popularity in the region during the 1960s, when major coastal lake cities and college campuses throughout the area became hotbeds for extreme political and social movements. Although the term is still common in many areas of the Great Lakes, the term is commonly linked to the cities of Chicago, Milwaukee, Detroit and Cleveland (which prefers the term “North Coast”).
 
Places near the Gulf Coast, such as Houston, Texas and Atlanta, Georgia, may also use the term “Third Coast” to refer to the country’s southern coast. Additionally, the city of Nashville is sometimes referred to as the “Third Coast” because of its role as a center for country music.
 
About.com: Austin
Q. What is the Third Coast?
From Jacci Howard Bear
(...)
A. That part of the United States bordering the Great Lakes, especially Chicago has been referred to as the Third Coast for several decades and is home to the Third Coast International Audio Festival. However, some southern states bordering the Gulf of Mexico (the Gulf States) are also commonly referred to as the Third Coast. And it’s not just coastal cities where the term Third Coast is used. Inland cities, including Atlanta, Georgia and Austin, Texas are part of this third coast. In Texas the third coast centers on Houston but includes Central and East Texas and parts of Louisiana too.
 
While some might use the term third coast geographically, it’s really more of a statement about culture—everything from food to fashion to politics and most especially music and film. The Third Coast is a departure—culturally and geographically—from the cultural centers of the East and West Coasts.
 
In Texas and Austin, the Third Coast is associated with music—especially country and hip-hop—activism, and film.
     
Urban Dictionary
1. third coast
dirty south; hip-hop slang for the southeast
After a decades of east coast/west coast rap domination, third coast artists are becoming the hottest thing in hip-hop
by Nick Victim Apr 20, 2004
   
2. third coast
The Gulf coast. Originally used to refer to the Texas coast and sometimes Texas in general, it now has expanded to generally mean the entire American region bordering the Gulf of Mexico.
While the term has been used for several decades in business names and catch phrases, the recent attention that Southern Hip Hop music has garnered has brought it into the limelight.
“The South is hip-hop’s Third Coast, the final element making up the genre’s worldwide holy trinity.”
by JayJay Jackson NYC Apr 22, 2006
   
3. third coast
Apellation describing the state and cultural region centered on Houston, Texas including Central and East Texas and Southern Louisiana used in several different contexts (film, hip hop and other music, left activism, etc).
This term is claimed by several other regions as well (Chicago, Western Michigan, the Southeast), but it properly refers to Texas.
Richard Linklater and Wes Anderson put the third coast on the indy film map.
Chopped and screwed, third coast style.
by dacoit boston Apr 28, 2006
(...)
6. third coast
Gulf coast, began in the days of rap with the whole east coast (first), west coast (second) rivalry.
I’m third coast born!
by 420island Texas Apr 24, 2006
 
7. third coast
Gulf coast of Texas and Louisiana. Refers to a genre of music including Austin-based alt-country, folk, and zydego.
The third coast radio program plays artists like Robert Earl Keene, and Buckwheat Zydego.
by NikkLou Washington DC Apr 22, 2006
 
(OCLC WorldCat record)
Title: The Third coast :
contemporary Michigan poetry /
Author(s): Hilberry, Conrad.
Scott, Herbert,; 1931-
Tipton, James,; 1942- 
Publication: Detroit : Wayne State University Press,
Year: 1976
 
(OCLC WorldCat record)
Title: Third coast archives.
Publication: Milwaukee : House of Words,
Year: 1976-1982
Frequency: Irregular
Description: No. 1 (Feb. 29, 1976)-no. 21 (winter 1982).; 21 v. :; ill. ;; 22 cm.
 
5 August 1979, Atchison (KS) Sunday Globe, “Combat Oil Spill,” pg. 1A, col. 7:
CORPUS CHRISTI, Texas (AP)—(...) Officials say the impact on the South Texas shoreline—“America’s third coast”—could be catastrophic, endangering a lively tourist trade at beach resorts, killing wildlife and wiping out catches of Gulf of Mexico shrimp.
 
31 July 1981, Elyria (OH) Chronicle Telegram, tv section, pg. 9, col. 4:
10:30 P.M. - (25) EXCHANGE “The Third Coast” The style of life in Texas and the effects of rapid growth on Houston, the state’s largest city, are explored.
 
(OCLC WorldCat record)
Title: Third coast :
the magazine of contemporary Austin.
Publication: [Austin, Tex. : Third Coast Media,
Year: 1981- 
Frequency: Monthly
Description: Began in 1981.; v. :; ill. ;; 37 cm.
       
(OCLC WorldCat record)
Title: Down on the third coast
Corp Author(s): Cheezmo (Musical group) 
Publication: Austin, TX :; Katz Pajamaz Records,
Year: 1982
Description: 1 sound disc (12 min., 55 sec.) :; analog, 33 1/3 rpm ;; 7 in.
Language: English
Music Type: Popular music
Contents: Down on the third coast (3:18)—The original hardluck kid (3:43)—Dreamin’ and schemin’ (2:57)—Circle (2:57).
SUBJECT(S) 
Descriptor: Popular music—Texas—Austin—1981-1990. 
 
(OCLC WorldCat record)
Title: FilmTexas.
Corp Author(s): Texas Film Commission. 
Publication: [Austin] Texas Film Commission, Office of the Governor.
Year: 1900s- 
Description: v.; ill.; 28 cm.
Language: English
Standard No: ISSN: 0731-4922; LCCN: sc 82-7036
Note(s): “News from the Third Coast.”
 
(OCLC WorldCat record)
Title: Third Coast Jazz.
Corp Author(s): Third Coast Jazz. 
Publication: Austin, Tex. : Austin Dance Umbrella,
Year: 1980s-?
Description: v. :; ill. ;; 28 cm.
Language: English
SUBJECT(S) 
Descriptor: Jazz dance—Periodicals. 
Named Corp: Third Coast Jazz—Periodicals. 
Note(s): Title from caption; description based on: v.3, no. 1.
 
(OCLC WorldCat record)
Title: Third coast review :
a look at art in Texas.
Corp Author(s): Aspen Art Museum (Aspen, Colo.) 
Publication: Aspen, Colo. (590 North Mill Street, Aspen 81611) : Aspen Art Museum,
Year: 1987
     
Google Groups: rec.music.hip-hop
Newsgroups: rec.music.hip-hop
From: .(JavaScript must be enabled to view this email address) (kari orr)
Date: 1995/08/18
Subject: Re: Geto Boys - Gangsta of Love?
 
finally some texas love. 2 albums released one on def american, with the gangsta boogie as the chorus and the grip it on that otha level released on rap a lot records with gangsta of love with the call me the gangsta of love hook as a bonus track not listed.
 
kari orr
house of phat beats
in texas the third coast where we rock the most
 
Google Groups: alt.rap
Newsgroups: alt.rap
From: James Phillips