Vancouver is a city on the north bank of the Columbia River in the U.S. state of Washington and the county seat of Clark County.
The width of the twin quilt is 66 +12 (for the two extra columns of 9 patches) + 4 (for the two extra strips of sashing) =82, which is a bit wider than your target of 78, but close enough. Plus, it's nice to have it a bit too large than a bit too small.
In America, the standard sizes for blankets are as follows: 1  Crib: 45 by 60 inches. 2  Twin: 66 by 90 inches. 3  Double: 80 by 90 inches.  Queen: 90 by 90 to 100 1  inches. King: 108 by 90 to 100 inches.