Gateway International Raceway is actually in Madison, IL. Which is a suburb of East St. Louis, IL and right across the river from St. Louis, MO.
Since a lot of people arent sure of where Madision IL is, its easier to say East St. Louis, but a lot of people dont know that East St. Louis is in Illinois, so they just say St. Louis, MO since its right across the river.
Kinda like people that live in suburbs around major metropolitan areas such as chicago. its easier for them to just say they are from Chicago instead of saying they are from... say... Stickney, IL
Growing up in East St. Louis myself, I learned quick that it is often lumped together with St. Louis and sometimes you have to verify which side of the river you need to be on.
and gateway is where I grew up racing