With this function, one or more open polylines will be automatically closed. If there is a gap between the first and last point of the polyline the function will draw a straight-line between the point and close the polyline.
Run the tool from the following location:
MOUS_ICO Toolbar: Tools > Auto-Close polyline
Command prompts for:
Select Polylines to close : Select objects: Pick all the polylines to be closed and hit Return