The geographical mile is an international unit of length determined by 1 minute of arc (1/60 degree) along the Earth's equator.
The Portuguese system derived their miles (milha geográfica) as one third of their league of three separate values.
The geographical miles of the traditional Dutch (geografische mijl), German (geographische Meile or Landmeile), and Danish systems (geografisk mil) all approximated their much longer miles—equivalent to English leagues—by using a larger division of the equatorial degree.
Instead of using one minute of arc, they all used four—1/15 degree—to produce a distance now notionally equal to 7,408 metres (24,304 ft) but actually differing slightly depending on official measurements and computations.
For example, Section 1301(a) of the Submerged Lands Act defines state seaward boundaries in terms of geographic miles.