What is the latitude of someone in the United States who sees the Sun at an altitude of 67.5° on June 21?
The maximum altitude of the Sun on June 21 (summer solstice) is at the Tropic of Cancer, which is at 23.5° N latitude.
Since the person is seeing the Sun at an altitude of 67.5°, we can calculate their latitude by subtracting the Sun's maximum altitude (90°) at the Tropic of Cancer from the observed altitude:
67.5° - 90° = -22.5°
Therefore, the latitude of the person seeing the Sun at an altitude of 67.5° on June 21 in the United States is 22.5° south of the equator, which is equivalent to 22.5° N latitude.