Apparently, this cemetery is big and difficult to navigate. I'm trying to reach office in advance to confirm hours and everything. Can't reach them so far. Details:
Address: 5400 Bay Parkway, New York, NY 11230
Phone: (718) 377-8690
Death: May 9, 1918
Burial: May 18, 1918
Visit: Saturday, Oct 6
Washington Cemetery (Jewish) McDonald Avenue and Bay Parkway, Brooklyn, NY 11230, Washington (Brooklyn) Founded 1867 County: Kings/Brooklyn 5400 Bay Parkway at MacDonald Avenue, Brooklyn, NY 11230 718-377-8690 Records can be retrieved alphabetically by deceased's last name, chronologically by date of burial, and by burial society. They have excellent maps of each burial society plot area.
Apparently, sections of the cemetery were managed by "Associations" that could represent county of origin. So I did a search for "Washington Cemetery" and "Association" and found this: