Nautical mile 1 sea mile", followed by "For most practical purposes distance is measured from the latitude scale, assuming that one minute of latitude equals one nautical mile". One tenth of a nautical mile is a cable length. The derived unit of speed is the knot, defined as one nautical mile per hour. The metre was originally defined as of the meridian arc from the North pole to the equator passing through Dunkirk. The Earth’s circumference is therefore approximately 40,000 km. The equatorial circumference is slightly longer than the polar circumference – the measurement based on this (40,075.017 km x x =
South Dakota Highway 240 Route 16 Alternate (US 16 Alt.), in addition to SD 40 along the eastern portion of the loop. These two numbers were used until the early 1970s, when the SD 40 number was replaced by an extension of SD 44 (which entered the park from the southeast rather than the northeast). Around 1980, US 16, which traveled concurrently with I-90, was truncated at its eastern end to Rapid City. Since US 16 Alt. no longer met the parent route, the route number was changed to SD 240. South Dakota Highway 240 South Dakota Highway 240 (SD 240), also signed as