In recent years, when I have presented talks or clinics about Pacific Fruit Express, I have often been asked the question, “How can I figure out what fruits or vegetables would be shipped from the area of my layout?” — or words to that effect. I have touched upon this topic, though not explored it in depth, in a previous blog; it is at: http://modelingthesp.blogspot.com/2011/08/few-words-on-packing-houses-and-produce.html . I showed there the resources available if you happen to model in Southern Pacific territory, as I do.
But what if you model some area other than SP territory? As you would quickly find by using Google, there are phenomenal amounts of information and statistics out there, about agricultural production. For example, the U.S. Dept. of Agriculture has a National Agricultural Statistics Service (NASS) with current and historical data by county. You can visit their website at this link: http://www.nass.usda.gov/Charts_and_Maps/Crops_County/ . Another similar source (I am not trying to be exhaustive here, only suggesting some leads of this kind) is a set of crop data, under the name Find The Data, which can be searched on their web page; one of their pages is here: http://farm-crops-county.findthedata.org/ .
There are also historical sources of other kinds. Many modelers are aware of the Sanborn fire insurance maps, available from the Library of Congress and from many local libraries and historical societies. These help identify facilities such as packing houses; the same is true of resources like historic telephone books, again something often archived in local and regional libraries. This will give you names of businesses and often their product(s).
If you can visit the area you model (assuming it is not where you live), a local librarian in that area may also be able to help with information about agriculture and crops in the area. They often know of special resources of historical information about their area. Another possible source is box labels for fruit and vegetables. In recent years, these have become collectible and both books and websites exist with extensive coverage. In some cases, these labels are specific about the particular fruit or vegetable, as with this Arizona cantaloupe label image sent to me by a friend, or this California tomato label from my own collection.
For many more, see: http://www.google.com/search?q=vintage+produce+box+labels&tbm=isch&tbo=u&source=univ&sa=X&ei=B56XU43JBIOMyATehIGgBQ&ved=0CDsQsAQ&biw=1092&bih=1013
For any area, produce may have been grown for relatively short-travel markets, such as into a city from the surrounding region, or much longer travel, to faraway regions of the country. Obviously the latter is more likely to be carried by rail, but high volumes of even shorter-distance crops were carried by rail before the Interstate highways became a network of effective truck transportation. That was certainly the case in my own modeling year of 1953.
So although I don’t think there is just one answer, or source of answers, to that question of what crops were shipped from your area, I do believe that a little digging will readily show that there is a lot of information out there. It all depends on how much you want to know.