What's the story with apartment numbers like "3G" and "5A"? Is it a NYC thing?

Every apartment building I’ve lived in, or even visited, uses just a numeral to identify individual units, of which the first one or two digits indicates the floor. But in TV shows, movies, and novels the characters often live in 3G or 5A. Presumably the number is the floor, and the letter identifies the unit on the floor, which is pretty straightforward and simple if there aren’t more than 26 units on the floor.

IIRC Jerry Seinfeld “lived” in 5A, in his show; then there used to be a long-running dramatic comic strip Apartment 3G. But do they still use this numbering scheme IRL? Is there any common thread running through the buildings where it is used–for instance, are they generally older structures? Are they bigger, better, and more desirable apartments? Or do they tend to be coops or condos rather than rentals?

The last apartment I lived in used letters. This was in the 1980s in Southern California. It was street address + letter for all your mail. IIRC, I lived at 1423D.

Hereabouts you see it in old buildings - the boyfriend lived in 11F when I met him. That was the oldest highrise in town, though.

Not just New York, I am sure.

I lived in an apartment complex that used letters in Calgary Alberta Canada. It was about 18 buildings that were in a large crescent around a park in the middle. Each building was numbered & each apartment has a letter. At one time I lived in 12L and later moved to 4G.

The were rather “project-like” buildings, built in the late 1940’s for single war vets. The apartments were huge, but in poor repair. I would have stayed longer too, had they not been planning on condoizing & rebuilding them all.

My dorm has numbers for the floor and letters for the room. So someone living on the fourth floor would be 4A or 4B or 4C or…

My apartment number here in Panama City is 15A.

Some parts of suburban Atlanta, Georgia had the same scheme in the 1980s.
They probably do now as well.

“TYLER: Raymond K. Hessel. 1320 SE Benning, apartment A. Small, cramped basement apartment, Raymond?
RAYMOND: How’d you know?
TYLER Because they give shitty basement apartments letters instead of numbers. Raymond, you are going to die.”

-Fight Club

If it’s a combined system like that, maybe the number is a building or floor designator, and the letter is the individual apartment?

One of the most famous of all time: 221B Baker Street - Wikipedia

Every apartment I have lived in was numbered in the form NX, where N is a floor number and X is a letter.

For several years I lived in Los Angeles in an apartment, the address for which was something like 1234 Main St. Apartment F.

Just a single letter for the apartment “number”.

Apartment 3-G is still running, btw.

What was the Golden Girls joke?

Blanche: I haven’t read Apartment 3-G since 1965!
Rose: Well, it’s later that same afternoon…

Apartment owners can do naming any way they like, so there isn’t always a consensus about it. I’ve never been to New York (lived in CA and WA), but I’ve seen plenty of places use numbers and letters.

One trend I’ve seen is that letters often get brought in at the beginning to designate buildings. A-305 at one place meant Building A, Floor 3, Unit 5. B-3 at another place composed of several triplexes meant Building B, Unit 3.

In terms of using letters for apartments instead of numbers, there are advantages for largish buildings that have many units per floor. A-Z gives you 26 apartments per floor without needing two digits. Since brass letters cost a couple of bucks each, that’s enough to justify it for a lot of cheap landlords. Plus, using M instead of 13 avoids superstition problems.

Not always. My last apartment building had the floors labeled with letters and the apartments on that floor labeled with numbers.

I never could figure out why this was, but thinking about it now, it makes a lot of sense. It was a pre-war 5 story walk up split into wings. It would suck to climb all the way up to the 5th floor looking for 5E only to find that the top floors were all 3-bedrooms, could only fit 4 apartments, and the one you were looking for was in the other wing. So what they did was run the letters down from the top floor labeled:


If you were looking for 4-F, you would see that the bottom floor of wing1 was E so it must be the top floor of wing2.

Of course, getting the elevator just made things more confusing since in there the floors were labeled with numbers. This made ordering take out an adventure. (“Yeah, I’m in Apartment 7 on Floor F which is the 5th floor in the 2nd elevator.” “Whaaa? You want food you come down now!”)

Then there was a numbering scheme with fractions that you rarely see anymore. I once lived in a Los Angeles single-story building with four units per street number (8 units for 2 street numbers, actually). They were numbered 2052, 2052 1/4, 2052 1/2, 2052 3/4, 2054, 2054 1/4…

I often wanted to address mail to 2052.75 instead of fractions, but I don’t think the post office would have been amused. They have trouble with square envelopes, charging more since they are non-rectangular.

In grad school, I lived in an apartment complex with three attached buildings. The buildings were 10, 7, and 4 stories tall, and the buildings were associated with letters. The first year, I lived in 419A (in the 10 story building), the second year, I lived in 404C (the 4 story building).

I’m unsure if the 8th, 9th and 10th floor apartments in building A had a letter designation, but I assume that they did.

In Baltimore, lots of old rowhouses have been converted into apartments, usually with two apartments per floor. Apartments are usually designated by the letter F and R, for Front and Rear.

It’s definitely not an NYC thing. I used to live in apartments in NC, DC and CA, all of which had number+letter addresses.

ETA: One was a new apartment complex (letters referred to apt. units within the numbered buildings), one was a rowhouse where the letters designated flats (floors) in the rowhouse, and one was an old Victorian hotel that was converted into an apartment building.

My building (a nine-story with six apartments per floor) is just numbers, but most of the apartments in the graduate housing area here are a mixture of letters and numbers. The building has a number, and then each unit in that building (4-8 each) has a letter. I think it’s partly to help break up the address a bit: An address like “1033 Grant Chamberlain” wouldn’t tell you whether it’s the 33rd unit in building 10 or the 3rd unit in building 103-- You’d need a hyphen or something. But “103C Grant Chamberlain” makes it clear that you should first find building 103, then look for unit C in it.

There’s a practical reason for designating apartment with a number/letter combination. In many buildings the floor plan is the same on every floor. For instance, apartment 3-A would be directly above apartment 2-A. Utilities and risers usually go up vertically. If there is a problem or need to designate a service area the location can be easily identified. "We have a problem in the “A” line or the “M” line or whatever. Also, those services are often zoned so that service to one zone can be shut down without turning off the entire building. Therefore, in the building there might be a notice such as “On Thursday we have to make plumbing repairs in the “D” line. Water will be shut off from 10 am to 12 noon.”