Geographers use ﬁeld pattern to describe how the countryside is divided up into allotments for cultivation or grazing, reﬂecting the history of ownership and administration. The term may also refer to the way in which individual ﬁelds are plowed. The typical ﬁeld pattern in New England is a crazy quilt of small, irregular parcels, their boundaries inﬂuenced by the contours of the land. Along rivers in Louisiana and the Southwest, ﬁelds are often laid out according to the old French and Spanish system of narrow long lots running at right angles to the watercourse. Meanwhile, in the Midwest the dominant pattern, dictated by the Land Ordinance of 1785, is a checkerboard of mile-square sections, their sides running due north-south or east-west, without regard to hills, streams, or other natural features. A corrugated ﬁeld is one in which neighboring strips are plowed in opposite directions, thus creating distinct ridges and troughs, to reduce erosion or guide irrigation water. An envelope ﬁeld, which suggests the merging of the triangle folds on the reverse of an envelope, is a type of corrugated ﬁeld.