Illustrator: Border effect for a path

Question

I'd like to surround a path with a border (see the third illustration below). However, I cannot get it done without using Path -> Outline stroke. This is very inconvenient, as Outline stroke replaces the original path with a new, much more complicated one, and it becomes much harder to edit the path later.

I thought that maybe some border effect exists that I don't know of. Something like Outer glow (see the second illustration), but solid rather than a gradient. Is there such an effect?

Answer 1

I found it! It's actually very simple:

1. Open the Appearance panel and add another stroke, two pixels wider than the green one. Make it black.
2. Drag it down in the Appearance panel, so that it is below the green stroke.

Voilà - a border!

Answer 2

Try this:

Copy your original path. Lock it.

Paste in place.

Turn your copy into outlines. Unlock all.

Group the outline and the original.

It's a bit quick-and-dirty, and if you make changes you have to redo this sequence, but it preserves the editing capabilities you want.

Answer 3

This answer shows you how to use sub-layers inside your outline layer. This way you can acchieve the result @Lauren Ipsum is describing but with

1. the flexibility to move your lines around and not accidently missing one of the underlying lines and
2. having the possibility to save your "style" and reusing it on other lines later.

Answer 4

You can add more stroke in Appearance from Window/Appearance. Then Use the Stroke panel in Window/Stroke to Align Stroke to outside.