Combine Seperate Features within the same Shapefile

Sometimes, when working with shapefiles in ArcMap, it may become necessary to create one feature from multiple ones. For instance, if you have created a series of lines that represent a wall, you migth want these seperate features to combine into one feature (thereby sharing one row in the shaepfiles attribute class). This tutorial will walk you through selecting multiple features within a single shapefile and combining them into one feature.

Programs Used
ArcMap

For the purpose of this tutorial, I will be combining multiple line features in a line shapefile. The image below contains several features that I want to combine, so that they all share one row in the attribute table.

The first step is to begin editing in ArcMap; select 'Begin Editing' from the 'Editor' drop-down menu.

This will allow you to actively change the featurs in this shapefile. Now, you should open the shapefiles attribute table by right-clicking on the layer name in the table of contents window (left hand side window in ArcMap as shown above).

This will open the attribute table. You can see the different features (each represented by a different row) within the shapefile).

After positioning the attribute table out of the way (you can always minimize it until later), we can begin editing the features. First, activate the 'Select Features' tool by clicking the button shown below:

There are two ways to select multiple features, which we need to do before ArcMap will combine them. The first method is to left-click on each feature while holding the shift key, which will highlight each feature as it is clicked

Or, you can simply hold down the right mouse button and drag a selection box across the screen, like so

A box is created using the right mouse button

that will select all features within it

When all features are selected in the ArcMap window, they are also highlighted in the attribute table

Now that you have selected the features you wish to combine, select 'Union' under the 'Editor' drop-down menu, which will create a new feature composed of all the selected features. This will appear as a new row in the attribute table.

Now, you have to delete all the other features that you just combined, because they still exist as duplicated data at this point. Simply use the attribute table and hold down the Ctrl key as you right-click each row with the mouse, then hit delete. If the other features had attribute data, that will need to be re-entered at this point.

The final product will be one feature, corresponding with one row in the attribute table. To finish, simply click 'Save Edits' underneath the 'Editor' drop-down menu.

That's it, you have now combined multiple features within one shapefile into one feature. This is a very useful tool if you are working with CAD drawing, which typically import into ArcMap as a mass of features, which can be quite confusing and untidy.