How do you know plattsburgh is the state in which altitude of polaris is the highest?

Is astronomy, star coordinates can be given by two systems:

1. Altitude-azimuth - not fixed, and depends on the observor's location and the time when he is stargazing. It is basically useless for serious astronomy.

2. Equatorial - fixed coordinates, defined as right ascension and declination, which for a given star would be the same anywhere on Earth.

Altitude or elevation (used interchangeably in astronomy) is defined as the angle in degrees from the horizon, or from the horizontal plane with respect to the viewer's eyes.

If all US states are included, the highest altitude of Polaris, aka Alpha Ursae Minoris or the North Star, occurs in the northernmost state, Alaska. The town of Barrow, Alaska is the northernmost settlement in the US, at 71°17'44" N, and thus sees Polaris at its highest altitude.

Within the contiguous US (CONUS, the 48 states), the northernmost incorporated location is Sumas, Washington, with a latitude of 49°00'09" N. Thus that would be the place in the CONUS where Polaris is at its highest elevation. Plattsburgh, NY is at latitude 44°41'43" N, which places it 4°18'26" south of Ramus. It is the northernmost city in NY (there are a towns farther north), so the residents of Plattsburgh can see the Pole Star at the highest elevation of any city in the state.

Interestingly, the elevation of Polaris changes slightly as Earth rotates. It is 0.7° from the north celestial pole, so it draws a 1.4° circle around the pole in 24 hours. Its altitude varies by that 1.4° angle. Thus two towns at exactly the same latitude but on opposite sides of Earth would alternate in seeing the star at its highest altitude.

And to further complicate the issue, Earth's axis is tilted at 23.45° to the plane of its orbit around the sun (the "ecliptic plane"), and it wobbles. It's called precession. Envision a top or a toy gyroscope slowing down. The free end of the axis draws a circle as its speed decreases. The analogy is not exact, since both poles of Earth precess, but the result is that over a period of 25,920 years the poles describe a 46.9° circle in the sky. In about 13,700 AD the star called Vega (Alpha Lyrae) will be the pole star, within 4 degrees of the north celestial pole, and Polaris will be just another bright star with no special significance.