That depends a lot on who you ask. I've been told by some "old folks" I've met that WCS started with R&R and Jump Blues. When I first learned it in the mid 90s people danced almost exclusively to blues and R&B.
One of the first westie compilations I saw was "Roll up the rug" Vol. 1; here's the track listing:
Seven Long Days [Charles Brown], 3:57, 138
Two-Fisted Mama [Katie Webster], 3:22, 144
Satisfy Susie [Lonnie Mack], 4:30, 141
Black Satin [Katie Webster], WC Swing, 3:45, 114
Don't Mess with My Man [Irma Thomas], WC Swing, 2:20, 126
No Broken Hearts [Elvin Bishop], 2:50, 124
Red Beans [Professor Longhair], 4:09, 139
Meet Me with Your Black Drawers On [Professor's Blues Review w/Gloria Hardiman], WC Swing, 4:31, 122
T-Bone Shuffle [Albert Collins, Robert Cray, Johnny Copeland], WC Swing, 4:54, 130
I'm Gonna Forget about You [Marcia Ball], 2:54, 130
Walkin' Blues [Johnny Heartsman], 3:44, 146
Good Times [Eddie Hinton], 3:47, 126
Don't Do It [Little Charlie & the Nightcats], Swing/Twist?, 4:26, 146
A Good Fool Is Hard To Find [Albert Collins], WC Swing, 4:15, 130
Sure Had a Wonderful Time Last Night [Koko Taylor], Swing, 3:05, 120
Soul Food [Elvin Bishop], WC Swing, 2:45, 130
RUTR Vol. 2 is similar:
The Hunt Is On [Johnny Adams]
Change in the Weather [Buddy Guy]
One Bayou Drive [Roomful of Blues]
Doctor Blooze [Bluesiana Triangle]
Early One Morning (acoustic version) [Kenny Neal]
My Ordinary Girl [Tommy Ridgley]
Your Mama Don't Know [Nathan & the Zydeco Cha Chas]
Built for Comfort [Robert Lucas]
Honkey Tonkey [Koko Taylor]
Pop That Coochie [Beau Jocque]
Natural Born Lover [The Smokin' Joe Kubek Band]
It's Obdacious [Greg Piccolo]
My Baby Didn't Come [Mark Ford with the Robben Ford Band]
Imitation of Love [Johnny Adams]
Toughen Up [Lloyd Adams]
On Monday [Red Knuckles and the Trailblazers]
The "essential" westie compilation CDs are "Swingin' the blues Vol 1-5". There is very little pop music on those CDs; again, the focus is on blues.
Here are links to those CDs with some samples:
Vol. 1:
http://www.amazon.com/exec/obidos/tg/de ... ce&s=music
Vol. 2:
http://www.amazon.com/exec/obidos/tg/de ... ce&s=music
Vol. 4:
http://www.amazon.com/exec/obidos/tg/de ... ce&s=music
In the mid-late 90s, dancers from the mid-west started showing up at more and more competitions outside of their regional events and they danced to a lot of pop/dance music. The high energy of the music at a similar tempo to the blues music made it ideal for competition and I think it was the competitors who really changed the flavor of the social dancing.