//Code for defining a geographic coordinate system for a feature set
public static void AddingACoordinateSystemToFeatureSet(FeatureSet fs)
{
FeatureSet CopyFS = new FeatureSet();
ProjectionInfo dest = default(ProjectionInfo);
//Copies the selected layer to a new feature set
//Prevents the original file from being edited
CopyFS.CopyFeatures(fs, true);
dest = KnownCoordinateSystems.Geographic.World.WGS1984;
//Adds the geographic coordinate system to the feature set
CopyFS.Projection = dest;
//Saves the feature set
CopyFS.SaveAs("C:\\Temp\\US_Cities_GCS_WGS1984.shp", true);
Console.WriteLine("The feature was successfully been projected.");
}