I collect them because I think the cards are stunning - not because they have any great value. Ultimately, the only reason to collect is because you like the item, not because of the value. There are more dealers today who buy certain countries they are interested in. Well with antiques it is just the opposite. New Hampshire Pottery sells better in New Hampshire than in Colorado and Roseville sells better in Ohio than in New Mexico.
Local pride has quite a bit to do with it.
With paper items and other ephemera it is the local history buff that is more interested in the item than someone who lives hundreds of miles away. It is easier to sell items about a place to people who live there, unless it is a major resort or tourist area. In that case you have to take the coals back to Newcastle. Unless you know the towns that are salable you can amass a whole album of Broadway, or some other unsaleable town. What you need to do is go toward images.