As pointed out in at least one of the replies to this post, a good place to look is on the website of Allegany County Historical Society.
If you go to the site and then click "Photo Gallery" you will see a Maps choice. It includes several maps of the county.
We also have additional maps available at the Society and will respond to email requests or refer you.
Finally, the website: www.alleganyhistory.org
Or, the page directly to the Maps section:http://gallery.alleganyhistory.org/album/Maps
Ron Taylor, Webmaster; ACHS