The location of the Write-On varies, depending on your version, so find it by doing a quick search in the Effects & Presets field.

Drag and drop this onto your Line layer.

Select the Mask Path by clicking on the Mask 1 beneath the Line layer.

Copy and paste this layer into the Brush Position layer within the Write-On effect.

You should now see a series of key frames that correspond to the pen path you just drew.

Set your brush size larger than your route line. For an animated reveal that closely follows the bends in your route, make it just a tad larger. If your Pen path is less precise, you may have to use a larger brush size. We used a setting of 20.

Change the Paint Style to Reveal Original Image. This is located at the bottom of the Write-On options.

Depending on how much larger your map is than the NTSC preset, you may see only a portion of your image. Don't worry, we'll see it all in a moment. Now hit the RAM preview button to view what you have so far.

It is likely you will want to change the speed of your animated line. To do this, first highlight all of your key frames, then go into the graph edit mode and drag the group to the right to slow down your line or to the left to speed things up. We quickly lengthened the timing of our line from two to nine seconds with this method.

Now for more fun, parent the line layer to the Map layer and, with the base layer now selected, let's zoom into and pan (scale and position) the map to where the line begins and create a key frame.

Drag the timeline cursor to the end of the animated line, pan the map to that point and create another key frame.

Analyze your movement and add additional key frames as necessary to track the tip of your travelling route as it meanders down the state.

To smooth out the movement further, adjust the Brush Position key frames left or right.

You now should have a simple animated line that closely follows your defined path. If you want to push this effect even further, look into modifying this base animation with the 3D effects that come packaged with After Effects.

Contributing editor Brian Peterson is a video production consultant, trainer and lecturer.

Click here to View the finished effect here.