Tenement Clotheslines

A classic and distinctive feature of urban residential areas in the first half of the 20th century and earlier: a clothesline strung between buildings two or more stories in the air. Tenement Clotheslines usually span courtyards, alleys and narrow streets between apartment buildings; they give a sense of a neighborhood that is at best middle class and probably lower. When found they are almost always populated with at least a couple items of drying clothing, and they are rarely alone -- in works of visual fiction, at least, there are normally at least three, at slightly different levels and distances from the viewer.

With the invention of the modern clothes dryer the practice has all but vanished, at least in the United States, but it can still be found if you know where to look.

Although one might consider them an eyesore they seemed to have had an aesthetic appeal for photographers and artists, especially in the early part of the 20th century. Numerous photographs and paintings were made of urban laundry hanging to dry, thoroughly documenting the practice for later generations.

This is primarily a visual trope -- essentially a piece of urban set-dressing -- but can make appearances in text works.

Related would be the practice of Japanese apartment-dwellers drying clothes on a circular rack hung on their balcony.

Examples of Tenement Clotheslines include:

Anime and Manga

In the DVD-only episode of Aria the Origination, Akari and Aria deliberately go looking for Tenement Clotheslines with clothing on them -- and find some.

Film

What is likely the earliest instance in film can be found in Amarilly of Clothes-Line Alley, a 1918 silent romantic comedy film starring Mary Pickford. Its title character is the daughter of an Irish washerwoman in an unspecified city. Establishing shots show the Alley with the clotheslines spanning it.
The use of this trope in various Golden Age of Animation cartoons (see below) was referenced in Ralph Breaks the Internet when the Disney Princesses quickly set up a dress hanging from a couple of lines for Ralph to fall into when he plunges from the top of a tall building.
In one sequence in The Secret Life of Pets, Max tries to escape a gang of alley cats, but in the process gets thrown between clotheslines spanning an alley in New York.
Prominently seen throughout the 1961 film West Side Story, in keeping with what the West Side of Manhattan looked like in the 1950s. (See Real Life, below.)
Also prominently displayed several times in the trailer for Steven Spielberg's 2021 version of West Side Story for exactly the same reason.
When Peter makes his leap from the top of a building in an attempt to get his powers back in Spider-Man 2, several lines of clothes are strung directly below him, through which he plunges when his powers don't oblige.

Literature

The 1915 novel Amarilly of Clothes-Line Alley by Belle K. Maniates, on which the 1918 film was based, also includes descriptions of the lines high above the alley and the clothes drying on them.
Laundry Day, a 2012 children's book by Maurie J. Manning, is set in a New York tenement in the very early 20th century. Its protagonist searches for the owner of a piece of red silk that fell out of the sky, and along the way uses the clotheslines to travel between buildings. The cover of the book features two such clotheslines, strung from a fire escape.
"The Adventure of the Clothes-line", a short mystery story spoof from 1915 by Carolyn Wells, features the Society of Infallible Detectives attempting to unravel the matter of a beautiful woman in evening dress found hanging from a clothes-line over a tenement courtyard on the East Side of London.

Video Games

Part of the action of the 1984 game Alley Cat -- a primitive Platformer -- involves guiding the titular alley cat along clotheslines spanning the alley; the cover of the game actually shows the cat desperately clinging to a item of clothing clipped to such a line.
Clotheslines can be found hanging between buildings in several of the zones in City of Heroes, most notably Kings Row and the southwest corner of Brickstown.
Several of the levels in the basketball-dunking game Hoop World! use a collection of five or six tenement clotheslines strung between two adjacent buildings as an obstacle you must fall or bounce through in order to slam dunk your basketball through the target hoop.

Web Original

As seen in the page image, several clotheslines are strung overhead between the buildings on either side of the street down which Roman Torchwick and his thugs stroll in the first few minutes of the very first episode of RWBY. Interestingly, we never see such clotheslines in Vale ever again.

Western Animation

Frequently seen in theatrical cartoons -- such as Looney Tunes, Tom and Jerry and others -- where someone falls off a tall building and into/through multiple clotheslines, often changing outfits with each line they pass.
One of the earlier segment openings for Rocky and Bullwinkle has Bullwinkle being prevented from falling to his death by falling into an outfit on a clothesline.

Other Media

The Getty Images archive not only has dozens of photos of tenement clotheslines, it actually sells prints of them.

Real Life

Although not seen nearly as much in the United States as it was in, say, the 1940s, real-world examples can still be found in some neighborhoods. And it's still surprisingly common in Europe, as a simple Google search will reveal.
The Museum of the City of New York has an entry on its blog about the clotheslines that were frequently found spanning city streets in the early part of the 20th Century, lavishly illustrated with period photographs.
The Ephemeral New York blog also has a well-illustrated entry entitled "What tenement clotheslines said about New York".