Sanborns before 1890 ?

[Clam]

Does anyone know how to get or have any sanborn maps that are prior to 1890. That is the earliest that Proquest goes for the Baltimore area.....

 

[CALDIGR2]

If that is all that proquest has then there probably aren't any older. They have the entire LOC collection scanned. !890 maps still show the features and existing structures, as do the later ones. The earliest maps for my town, Sacramento, CA, are 1895.