Trimming a lot of lines to a map extent has always been a real challenge in Illustrator. And there always seem to be extras coming out of GIS! There have been a number of third party plug-ins over the years like the Graffix cutting tools, but those no longer work in CS 5. The kind folks at the Swiss Federal Institute of Cartography (ETH) have a nice set of tools, including the Area Builder that does the job, but all the menus are in German (Google Translator sorts that out quickly). But now, Adobe has granted us the Shape Builder Tool, which natively joins overlapping polygons, like separated lakes, or creates polygons from overlapping linework. In its negative function, it can cut dangles right to our map frame, which is all we could have ever hoped for. Watch the video for a short demonstration of this practical and powerful tool.