You may have heard of Polk's city directories, but there are other companies that published city AND rural directories. These are commercial products, so were developed to help businesses.
The earliest Portland City Directory was published by S.J. McCormick in 1863. It included information on new buildings and newcomers, on fires, city improvements, locations of fire stations and alarms. It also included the names of the men who lived in the city -- and the names of some women. (Primarily those who owned a business, had an occupation, or were unmarried, living outside of the parental home.)
Businesses paid to be listed in the Directory; some purchased highly detailed advertisements, while other smaller businesses like neighborhood general stores simply listed their name and location.
Another important value to business beyond advertising, was the list of residents in the city. If someone wanted to rent or buy services from a business, the Directory could be checked to find out if the person lived locally, and where; in later years a check of earlier directories under the name, would let the business know how long they lived in the City, what their occupation was, and whether they moved often. All information that helped a business decide whether to extend credit to a customer, to hire someone to do a job, to lease or sell to a person.
The best way to find these kind of directories in the library catalog is to search using the name of the city or the county and the word "Directories" as a subject keyword search; eg, Wasco Directories. Eugene Directories, Baker Directories.