I've caught trout by ripping a jig through a hole, dead-drifting it with the current, or swimming it near the surface. I've even had trout cruise by and pick them off the stream bottom. Probably for the same reasons they like Woolly Buggers or small streamers. The undulating silhouette of a small jig suggests a worm, larva, nymph, or minnow that's worth a closer look to a trout. I also figured out in a hurry I needed some special equipment to pitch them where they needed to go.
Thin diameter is important because it allows longer casts.
If you don't, the line hangs up on the spool and shortens your casts. Southeastern Minnesota isn't the only place where trout eat jigs, of course. They'll work in any trout stream. Jeresek has fished his favorite lures in Western waters, for example, where cutthroats, rainbows, and browns all responded well to the same patterns he uses at home. The following specialty suppliers can help.