I live in the City and County of Santa Barbara . . . but it’s not quite the same as in SF (where the city and county are coterminous, and if I’m not mistaken share government.)
If you grew up in the South either in or adjacent to a dry county, I’m sure you were very aware of the counties and their borders.
Douglas County, Oregon. I can’t imagine someone not knowing their county, but having never lived back east, maybe its not so important there.
I worked at the reference desk of Cleveland Public Library (the main one downtown). I was never asked what county Cleveland is in… somehow the name Cuyahoga County is well known to its residents… but I did get some doozies. We were instructed never to answer questions off the top of our heads, even if we knew the answer right off; we always had to look it up in a reference source. One time somebody called to settle a bet. Is 40 spelled forty or fourty? I swear I was such a good little librarian I went and pulled out the dictionary and looked it up to prove that there is no such word as fourty, which I don’t need to consult a dictionary to know. I felt ridiculous—it can take like 10 times longer than really necessary to answer a question that way, while people are lined up in front of you, waiting their turn— but hey I was following orders. I’m so glad nobody called to ask what county we were in.
I live in the second-highest-income* county in the US. Which is bordered by the first-highest-income county on one side and the tiniest county by area in the US on the other side.
(Fairfax County, VA, bordered by Loudoun and Arlington counties)
*Which is not a desirable distinction when one’s own income totally sucks… well, at least we have a good public library system; I wonder how much they get asked what county this is.
I knew San Ber’dino right off from your description. On county maps of the US it’s really hard to miss noticing, the way it dwarfs all its neighbors. It’s celebrated in song.
It’s so nice to hear Pennsylvania’s Allegheny and Cambria counties mentioned here, my ancestral stomping grounds. In my genealogies those are the two names I keep seeing over and over, where practically all my ancestors in that line lived since almost forever.
… I knew it when I lived in Miami (Dade) but, uh, what county is Philadelphia in? wanders off in search of county info for Philly Ah neat, it’s called Philadelphia county.
That county information is also useful when tracking tropical weather systems. (Right now, we’re hoping for a little one to break the dreadful drought.)
I checked Wikipedia; Harris County is the 3rd most populous county in the country. The town of Harrisburg was founded in 1823 by a guy named Harris whose grandfather had founded Harrisburg, PA. Harrisburg was briefly the capital of the Republic of Texas but Santa Ana burned it in 1836 & it never fully recovered. Sam Houston beat Santa Ana in the vicinity, so a new town was built & called “Houston.” The town grew to a city & annexed Harrisburg but the county kept the name.
Oh, and for those who ask “omg how could someone not know?”, in my case part of the reason I didn’t know that when I lived in Philadelphia I was also in Philadelphia county is that the things that said “Miami Dade” or “Dade County” down there said “Philadelphia” in Philly. Since I never needed to contact the county directly in either place, I didn’t care enough to find out that this didn’t mean that those services were managed at different government levels in the two locations, but that the names of the two government levels in the second location happened to be the same.
That’s one of the cases where the city and the county have the same boundaries and hence the same government. (Another well-known case already mentioned is the City and County of San Francisco.) In cases like these, if you want a county-level official, you go to the city hall. Sometimes the city and county have different names, e.g., Louisville, Kentucky, and Jefferson County, Kentucky, share the same boundaries and have a city-county government.
And there’s one case where a city consists of more than one county: New York City consists of Bronx, Kings, New York, Queens and Richmond Counties – though those are all better known as boroughs of the city. (That’s not the same as a city being in more than one county, but not sharing boundaries – I live and work in cities that have spread into three counties, i.e., Columbus and Dublin, Ohio.)
I didn’t vote in the poll because I haven’t lived in the US for a long time, but when I did I certainly knew what county I was living in: born and raised in Philadelphia County, although what was left of the county government was vestigial and utterly useless. Then we moved to Delaware County on the other side of City Line. I am not sure what services we got from the county, but the marriage license office was in Media, the county seat. Then I spent two years living in New York County (coterminous with Manhattan) but I was unaware of any county function. Finally I lived in Champaign County, IL and I still write to the county clerk in Urbana to request an absentee ballot.
I am slightly surprised to discover that New England even has counties. Towns seem to play the role that counties do elsewhere.
I’m guessing that most of these people have heard about the internets but never actually seen them. So your poll is probably going to be skewed.
I worked in real estate in New Jersey for 26 years, where, due to duplication of names, every single freaking legal document has to have the name of the county and the place designation (City, Township, Borough) on it.
I have typed “Bergen County” about a million times.
Also, weather alerts here are given by the geographical local and county name ; i.e., northwestern Bergen County. You learned pretty quick when it’s a tornado alert.
Well, I live in the City and County and *State *of New York. Don’t think it gets easier to remember than that. 
Harris County, TX.
We don’t have that problem with counties, but we do with townships and boroughs. (Local government entities don’t cross county lines.) If you live on one side of the dividing line, you’re covered by one entity; if you live on the other side, you’re covered by another entity. (No joke. I was in a car accident once, and because it happened on the southwest corner, investigation was under the purview of the state police. If it had happened on the northwest corner, it would have been the borough police.)
IIRC, it works the same way in Texas, where the counties are responsible for the residents within their legal borders, regardless of city boundaries. Therefore, if you live in Bexar County, Bexar County provides your county-level services, and you’re bound by the laws of Bexar county. Ditto for Comal and Guadalupe counties.
I live in Ingham, one of 83 counties of Michigan. I’ve been working with state data for so long I know them most of them by the number that the state uses for them.
I didn’t know New Jersey had tornadoes.
So, when people ask where you are from, you just say “Manhattan”? 
Blows my damned mind when people don’t know what county they live in, and also if they live in the city or not - this past mayoral election was contentious, and plenty of people got turned away at the polls surprised to find they didn’t live in the city. WTF?
Ingham County is unique: it’s the only county in the U.S. containing a state capital (Lansing) where the county seat (Mason) is not the state capital. I’m guessing that BobLibDem works in Lansing.