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Well, it depends too how crisp you want those lines. Another option would be to use a hard brush or the pencil, click where you want to start, go to the end of a straight line before it turns, hold down shift and click again. Repeat. Do this on a layer above your map.

The wand doesn't work bad if you click outside the line to isolate it, then you can refine the edge, choose white background, smooth it a small amount and narrow or widen it, like ALB suggested. Then you can fill the new selection with black, on a new layer, and this might work.

But if you want really crisp edges, the pen tool will work best. Since you have essentially straight lines, all you have to do is make your line down the center of the map guideline, then activate the pen tool path and go to edit>stroke and choose the pixel width you need. This is similar to the first method I described. Again make all these marks and strokes on separate layers.

Try the assortment we've suggested and see what works best for you.