How to make Objects follow a path (illustrator) (like on the las vegas sign)

Pattern brush.

• Draw 1 light and create a rectangle around it with no fill and no
  stroke. Move the rectangle behind the light artwork.

• Drag all that to the Symbols Panel to create a symbol of it. (This
  step just makes editing the light easier later, and is not
  mandatory. To edit the light later, just double-click the Symbol in
  the Symbol Panel.).

• Now that the light is a symbol… drag it from the artboard to the
  Brush Panel and choose Pattern Brush…

• Now just draw a path and click the brush in the Brush Panel.

• You may need to double-click the brush in the Brush Panel and adjust
  some settings….

Be aware, this brush is not set up with corner artwork. For this reason any sharp corners will not have lights on them, You’ll want to use rounded corners to get the light pattern to appear. A brush with corners can be configured. However, creating corner artwork can be a very time-consuming and detailed processes and is not as easily described in a single post. If you need corners, I’d suggest a Google search for “Illustrator Pattern brush Corners tutorial”. You’ll find much more information than I can provide here regarding corners.

Additionally….

If you set the Colorization method to Hue Shift and then designate the color of your bulb as the Key Color….

You can then change the color of the lights by simply changing the color of the stroke on your path…..