On April 21st, the sun is directly overhead at noon at the Tropic of Cancer, which is approximately at 23.5 degrees North latitude.
It is locally noon.
Tropic of Capricorn
The Tropic of Cancer ... roughly 23.5 degrees north ... is the most northerly latitude where the sun can ever appear directly overhead.
8 degrees north
There is no latitude on earth at which the sun would be directly overhead at noon on the equinox and the solstice.
It never is overhead at noon because Texas is not in the northernmost point where the sun passes directly overhead at noon.
A tropic of Capricorn is the southern boundary of the tropics that marks the southernmost latitude at which the Sun can be seen directly overhead at noon and it is parallel of latitude approximately 23°27′ south of the terrestrial Equator.
The latitude that best represents the location where the Sun is directly overhead at noon on April 27 is the Tropic of Cancer, which is at approximately 23.5 degrees north. This is because on April 27 the Sun is positioned directly over the equator during the spring equinox.
The sun will be directly overhead at noon for locations along the Tropic of Cancer (23.5 degrees north latitude) on the June solstice and locations along the Tropic of Capricorn (23.5 degrees south latitude) on the December solstice. In between those latitudes, the sun will be high in the sky but not directly overhead at noon.
The Sun is never directly overhead at noon for an observer at locations above the Tropic of Cancer (23.5 degrees north latitude) or below the Tropic of Capricorn (23.5 degrees south latitude). This is because the Sun is directly overhead at noon at least once a year along the Tropic of Cancer and the Tropic of Capricorn as a result of Earth's axial tilt.
Hawaii.