A visitor decides in seconds whether you are a city builder or a county builder
Geography is the first filter a St. Louis homeowner applies, and most pool sites make them scroll for it.
The City of St. Louis is an independent city and legally separate from St. Louis County. Someone in the Central West End and someone in Chesterfield both say they are in St. Louis, and they are describing different governments.
Put the answer above the fold in plain words: which counties, which side of the river, and whether you cross the county line at all. A short line of text does more here than a rendering.
If you serve the Metro East, say so where it can be seen. Illinois homeowners are used to being an afterthought on Missouri sites and they will leave rather than check.
The same line qualifies traffic out, which is the point. A builder who never drives to Florissant is better off losing that visit in two seconds than in a twenty minute phone call.