Danville is an unincorporated community and census-designated place (CDP) in Ferry County, Washington, United States. Danville is located on Washington State Route 21 near the Canada–United States border, 31 mi north-northeast of Republic, the Ferry County seat. Danville has a post office with ZIP code 99121. The population at the 2010 census was 34.
Danville is a small community, but it has a post office.
Danville is a small community.... there is a population of 34, so to say it is small is an opinion (and it is relatively small), but as stated in the text, it has a post office with ZIP code 99121.  I think the word but in my statement fooled the system.