> For the complete documentation index, see [llms.txt](https://zillion.gitbook.io/iredistrict/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://zillion.gitbook.io/iredistrict/preserve-existing-boundary.md).

# Preserve Existing Boundary

Video: <https://youtu.be/Z4TjWXc4lfk>

For redistricting, it is usually required to preserve an existing boundary as much as possible, or minimize the cross of a boundary. iRedistrict can satisfy this requirement.

In the optimization criteria panel, there is a boundary criteria. Enable this criteria and then load the boundary layer. For example, in the image below, we load the MN county boundary.

![](/files/-MJ-sHoXsy11g_-XZDQ8)

The green polygon layer is MN county. The unit layer is the MN tract.

![](/files/-MJ-v6az5zSdL-dc5s87)

Click run and get 10 redistricting plans. The plan boundary is along with the county boundary.

![](/files/-MJ-wCh-sHR6_mkXTuJD)

iRedistrict support more than one boundary criteria. Click the + button to add other criteria. The more boundaries to respect, to more compromise to make.&#x20;

![](/files/-MJ3vQm_MDT5B1c3FYMh)