* Circumpolar Stars: These are stars that never set below the horizon as seen from a specific location. This is due to the Earth's rotation and the observer's latitude.

* North Pole: The North Pole is located at 90 degrees North latitude. Any star that is above the celestial equator (0 degrees declination) will be circumpolar at the North Pole.

* US: The US is located at various latitudes, ranging from about 25 degrees North to 49 degrees North. The further south you are in the US, the fewer stars will be circumpolar.

In simpler terms:

* Imagine standing at the North Pole. You'd see the entire Northern Hemisphere sky, and all the stars in that half of the sky would appear to circle around the North Star without setting.

* If you're in the US, you're not as far north, so you won't see all those circumpolar stars. The further south you are in the US, the less of the Northern Hemisphere sky you can see, and thus, fewer stars will be circumpolar.