From the Pattern Description: We begin with this style not because it is the simplest (it isn’t), but because it is the most familiar to the majority of knitters. A classic raglan is constructed in this way: first, you make a seamless rectangular yoke, by increasing 2 stitches at each corner of the rectangle every other round; then, when the rectangle is big enough to cover the shoulder area down to the underarms, you divide it up into sleeve and body sections. The short sides of the rectangle become sleeves. The long sides of the rectangle become front and back sections; these are worked together as a seamless tube all the way down to the lower edge of the garment.

Location of Pattern: Basic Design No. 1 - Classic Raglan Pullover - from page 19 of Knitting from the Top.