Why argyle socks aren’t knitted in the round

I’ve gotten used to the idea that socks are knitted in the round because of their tube-like shape; knitting in the round means no seams to do up at the end. However, I recently discovered that argyle socks are an exception: the leg (and sometimes part of the instep) is knitted *flat*, and then a seam is sewn up the back of the sock, and then knitting proceeds in the round for the foot of the sock. I’ve become interested in argyles because I haven’t yet attempted any “colorwork” aside from horizontal stripes (which don’t require any special technique) and I’d like to try something more complicated. I wondered, then, why the instructions would be different for these socks. As explained by Moth Heaven (her sock (leg) is shown at right; the ribbing is at the bottom and the leg proceeds upwards):

If you knit across a row in intarsia, for example — dropping the pink to pick up the green, when you come back around again on the next row, the end of the pink yarn will be all the way over on the other side of the diamond. That is why intarsia is knit flat.

Again, I haven’t attempted any colorwork yet, so “intarsia” is still a vague concept (one I hope to clarify soon), but even so this explanation made sense to me. I love explanations! Knitting instructions, like cooking recipes, tend to be very prescriptive (do this, do that), without stopping to explain why. No doubt this is because there’s a lot of domain knowledge you pick up by experience, and the typical pattern or recipe writer doesn’t want to take the time to spell out the reasons for each step, but it sure helps you learn faster, have more confidence in what you’re doing, and gain the ability to adapt patterns without making a mess.

I also recommend the excellent step-by-step guide to argyles from the same site. I haven’t actually used it yet, but an argyle sock is rising to the top of my to-knit list. (She also appears to be using the magic loop technique — cool.)