How do I import a KML data file into Google Maps?

I'm surprised that they haven't offered you even rudimentary directions, but it's okay, I've got your geoback. :-) First off, though, I hope that it's actually a KML map file that's written in XML compliant language rather than an XML file, per se. KML is "Keyhole Markup Language" and it's named after the company that created the geographic specific language.

Anyway, you probably don't care about that!

Your first step is to go to Google Maps and make sure you're logged in to your Google account. if you don't have one, create one. How to tell? On the top right it'll either say "Sign in" or it'll show your email address if you are logged in.

Once you are logged in properly, you'll see the following:

Click on "My Maps" and you'll see a list of maps you've already created (if any) and the all-important "Create new map" link:

Choose that (no surprise!) and it'll give you an area where you can name your map, add a description and, when you're ready, an "Import" link:

When you choose to import a Google Maps data file, it'll give you the option of specifying the map's location online with a URL or finding one that you want to upload from your computer:

Click on "Choose file" and it'll pop up a standard choose file dialog window (this is on a Mac, but a Windows PC works the same):

Once I've picked the file I want to upload (a file that ends with ".kml") I click on "Choose" and now I'm back to the Google Maps dialog window again, but this time the file name shows up:

That's good. Click on "Upload from File" and, depending on how big the file is, it'll complete in a few seconds or a minute or more, with the next action being it displaying you a map with all the data points plotted:

On the left side underneath the fields where you can enter a title and description for the map it now shows a list of the imported data points with any descriptive material included in the KML file:

Last step. Find the "Done" button and click it and you have a public custom Google Maps file with all the information easily accessible:

I hope that gives you all the information you need to get this working!

In a different set of blog entries I'll explain how to turn addresses into Latitude/Longitude information, then you can pour that manually into a KML file, as I'll also explain. Stay tuned for that!