About editing shapefiles

You can edit shapefiles in ArcGIS with any license level (ArcGIS for Desktop Basic, Standard, or Advanced). However, there are a few factors to consider when editing shapefiles.

Editing shapefiles

Before you start editing, ensure the shapefile has the correct projection defined so ArcMap can display it with other projected data. Although you can edit data in different coordinate systems, it is generally best if all the data you plan to edit together has the same coordinate system as the data frame. This is especially important for shapefiles because shapefiles sometimes are created with an unknown coordinate system or have missing projection (.prj) files.

You can edit all the shapefiles in the same folder during an edit session. If the shapefiles in your map are stored in different folders, you are not able to edit them in the same edit session. You need to stop editing on the first folder, then start editing on the other folder. Keep in mind that a shapefile supports only one person editing it at a time, although multiple users can view it simultaneously. Attempting multiuser editing of a shapefile can result in data corruption.

Unlike geodatabases, shapefiles are not associated with an ArcGIS release number. You can create and edit shapefiles in a newer release and use and edit them in an earlier version of the software. However, layer files do have a release number, so you must save the .lyr file to the correct version if you need to share it with users who are working with an earlier software release.

Creating features with curves in shapefiles

Shapefiles do not support true parametric curves, including circular arcs, ellipses, and Bézier curves, so these shapes are stored as straight segments. True curves are fully supported in geodatabase feature classes.

When creating curves in a shapefile using the editing tools, the shapes initially may appear curved on-screen. When you save your edits, however, the curves are densified and the shapes are converted into a series of straight segments that approximate the shape of the original curve. For example, you are digitizing a school and are capturing curved features, such as a baseball field, with the End Point Arc or Arc segment construction methods. In a shapefile, the curves are replaced with a densified line composed of short straight segments. With a geodatabase feature class, the shapes are stored as true curves with only vertices at the endpoints of the curve.

Comparison of true curves in geodatabase feature classes with curves represented as densified lines in shapefiles

If you have line or polygon features that share curved edges, the segment densification that occurs in shapefiles may result in small gaps being created between features. Some scenarios in which you might encounter this include when using the Auto-Complete Polygon or Auto-Complete Freehand tools to create adjoining polygons with curved segments or when copying curved features from a geodatabase feature class and pasting them into a shapefile. The only way to avoid this is to use a geodatabase feature class, which can maintain the true curves and guarantee coincidence among them.