Combining Regions in IMPLAN allows users to create Regions of grouped geographies to analyze impacts beyond a single geography. The great part is once a Combined Region is created, it will always be available for use in a project!
Users can combine Regions in IMPLAN using the Map or List View. The Map View is the easiest method when there are a few areas to combine. However, when combining multiple regions at a time, this process can be streamlined by using the Region List. This article will showcase all methods of combining regions, identify features in the Region List View, and show ways to access previously Combined and Customized Regions.
COMBINING REGIONS FROM THE REGIONS MAP
Users can create a custom Combined Region in IMPLAN with just a few simple clicks. Note, that only countries, states, counties can be combined from the Map View; zip codes must be combined using the Region List View.
From the Map View on the Regions screen, select all of the Regions by clicking them from the map. Click More Options in the Selected Regions panel, then click Combine Regions.
A popup will appear asking to name the new Combined Region. Remember to give it a unique name, as this will now be saved to the user’s account and become searchable from the Regions and Impacts screens. The name can be changed later.
The spinning wheel icon will appear as IMPLAN builds the Combined Region. Once complete, the View Region Details button will appear.
The user can now proceed with the analysis by clicking Create Impact in the bottom right corner of the screen or click Save to add the Combined Region to a Project.
COMBINING FROM REGIONS LIST
The Regions List view in IMPLAN makes combining Regions a breeze! Access the Regions List view from the Regions screen by clicking List View, the second icon next to the Selected Regions panel. There are three views Users can toggle between by using the highlighted icons; the Map View, List View, and Combined & Customized View. Once a Data Year has been selected, it will remain active in all views until changed by the user.
The default setting on the List View allows users to add single Regions to their project by selecting them individually or using the Add All button. Use the arrows to expand Regions to smaller geographical units or use the dropdown menu to change those units from county to congressional districts or MSAs.
To Combine Regions from the List view, toggle on the Multi Select View option using the slider.
Once enabled, Regions will now display a checkbox next to the name to indicate their selection. Use the arrows to expand Regions to smaller geographical units, such as county and zip codes.
For example, to see all of the Counties in Alabama, click the arrow to expand the selection. This will list all 67 counties in Alabama.
If we wanted to see the zip codes for a certain county, say Bibb County Alabama, click the arrow to expand the selection. This will list all 8 zip codes in Bibb County:
Users may combine any state, county, or zip code together as long as the selected regions do not overlap. For example, the state of North Carolina may be combined with a county in South Carolina, but can not be combined to a county within North Carolina.
Click the checkbox next to the Regions that need to be combined and select Combine Regions at the bottom right of the screen. In this example, we are going to set up a Multi-Regional Input-Output (MRIO) analysis creating a combined region of all counties in Alabama, except Baldwin.
Doing this will prompt the user to name the Combined Region. Make sure to choose a unique name that is easy to remember as Combined Regions are saved to the account and searchable from the Regions or Impacts screen. The name can be changed later.
Once combined the new Region will appear in the Selected Regions panel on the right. From here users can explore the Region Details of the Combined Region, create additional Combined Regions, or add single Regions.
To add single Regions from the Multi Select View, select Regions using the checkbox, but use the dropdown menu to change from Combine Region to Add Region or Build Region. Selecting Build Region will add the selected Regions and also automatically build them. This can be a huge timesaver if there are many Regions to select in a Data Year that has not been used previously.
As this example shows, the user added Baldwin County to set up their MRIO.
After the Regions have been combined and/or selected, click Save to save them to the project or Create Impact to advance to the Impacts screen to add Events.
Now that the Regions are now Combined Regions, they will show up in the Combined & Customized View and will be accessible for use in any future projects. Users can add them to any project from the Combined & Customized View by clicking on the Add icon. From here users can also delete or rename any of the Combined Regions.
In addition to the Combined & Customized View, any previously Combined Regions can be found by using the search bar near the top left of the Regions screen or in the Group Region dropdown on the Impacts page.
NOTE OF CAUTION
Combined Regions can be built using country, state, county, zip code, congressional district, or metropolitan statistical area (MSA) Regions. This also includes US Territories, which can be Combined with other mainland U.S. Regions. Note that users cannot combine a previously Combined Region or Customized Regions. Users are free to combine any non-overlapping Regions from the list. The following warning will appear when it is attempted to select a Region that is contained in another selected Region:
We received this error message because we attempted to Combine Fresno County with one of its parent Regions, the state of California. No matter which approach we take to combine Regions, this will never work as it would count Fresno County twice.
Also, at this time the Region list is limited to selecting 500 Regions to combine at once. At the bottom right of the screen, a running total of all the Regions that have been selected is displayed. When the limit of 500 has been exceeded, a warning will appear and the Combine Regions button will be grayed out as unavailable.
Updated January 19, 2024