I am very familiar with the Migration categories and have been working to setup the high level categories. Unfortunately, that work has been delayed by another user that did not understand the structure and did not clarify any questions with the Categorization Project.
The correct Category is "Immigrants to New York" and is just a level in the Migration structure that ultimately should not have any profiles linked to it, and is used to navigate the category structure.
If you would like to work on specific migration events for an individual, please use the Migration Category App that was created to help understand where the profile should be linked, and the hierarchy of the categories.