Geography · Rung 11 of 12

Borders and time zones

There are natural borders, following a river or a ridge, and geometric ones drawn with a ruler: almost all of the United States' border with Canada is the 49th parallel, and much of Africa's was settled in Berlin in 1885 without asking anyone, which is why so many are straight and cut through peoples. Time zones were born in 1884 with the railways: 24 bands of 15° from Greenwich, though in practice they bend so as not to split countries, and all of China runs on one hour where five would fall. The date line zigzags across the Pacific to keep each archipelago on one side, and Nepal, India and Iran run on half hours.

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The world, country by country

Exercises from this rung

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  1. The border between the United States and Canada runs straight for over 2,000 km. What does it follow?

    • The Missouri river
    • The 100th meridian
    • The Rockies divide
    • The 49th parallel

    Why It was agreed in 1818 and completed in 1846, running from the Lake of the Woods to the Pacific. Drawing it on a map left oddities on the ground: Minnesota's Northwest Angle is a piece of the United States reachable only through Canada or across a lake, and Point Roberts is an American neighbourhood attached to Vancouver.

    easier

  2. The point is at 120° east. How far is its solar time from Greenwich?

    • Eight hours ahead
    • Four hours ahead
    • Eight hours behind
    • Twelve hours ahead

    Why The Earth turns 360° in 24 hours, so every 15° is one hour: 120 ÷ 15 = 8, and eastward runs ahead. Time zones follow that arithmetic but bend around borders: the whole of China uses a single zone despite being 60° wide, and at its western edge the sun rises at ten in the morning.

    in between

  3. Why does the international date line zigzag?

    • Because splitting a country across two days is unworkable
    • Because of a historical error never corrected
    • Because it follows an ocean current
    • Because the 180th meridian is not straight

    Why It follows the 180th meridian but swerves to keep Russia whole on one side and the Aleutians on the other, and it loops around Kiribati, which moved the line in 1995 so its whole archipelago shared a day and incidentally became the first country to see the year 2000. Samoa switched sides in 2011 to share a working day with Australia and New Zealand, and that year skipped 30 December entirely.

    harder