At the North Pole (90 degrees north) and South Pole (90 degrees south), the speed is effectively zero since that spot rotates once in 24 hours, a very, very slow speed.

To determine the speed at any other latitude, simply multiply the cosine of the degree latitude times the speed of 1037.5646.

Thus, at 45 degrees north, the cosine is .7071068 so multiply .7071068 times 1037.5464 and the speed of the rotation is 733.65611 miles per hour (1180.7 km/h).

For other latitudes...

10° - 1021.7837 mph (1644.4 km/h)

20° - 974.9747 mph (1569.1 km/h)

30° - 898.54154 mph (1446.1 km/h)

40° - 794.80665 mph (1279.1 km/h)

50° - 666.92197 mph (1073.3 km/h)

60° - 518.7732 mph (834.9 km/h)

70° - 354.86177 mph (571.1 km/h)

80° - 180.16804 mph (289.95 km/h)

In addition to the rotational speed of the earth spinning on its axis, the earth is also speeding at about 66,660 miles per hour (107278.87 km/h) in its revolution around the sun once ever 365.2425 days.