i don’t know about houston but the other two are logical inflection/control points for transportation/railroads between regions. it’s not as obvious as a city sitting at a major confluence or great harbor but there were defensible reasons for it.
missouri, kansas, and texas railway (KATY)
the midwest, especially kansas city and st. louis really built out infrastructure plugging texas into the greater u.s. transportation grid with all of those cattle being WALKED into missouri and kansas.