The Jacksonville Sanborn maps updated through 1949 are available on the Library of Congress web site:

Here is the link to Volume 1a:

<https://www.loc.gov/item/sanborn01286_008/>

Here is the link to Volume 4:

<https://www.loc.gov/item/sanborn01286_010/>

The other updated Volumes thorough 1949 are not available on online. Earlier years (1884 to 1913) are also available.

The Library of Congress is gradually scanning their entire collection to place online. They say in the collection information they do not post anything beyond a copyright date of 1922, but there are exceptions I have found like the above.

Bill Hirt