Why are wires made cylindrical and not any other shape?

Thank you for asking such an interesting
question!

The answer is that wires can technically be made
into square or triangle shapes or whatever you want, they just don't tend to be.  First,
let's look at how wires are made:

Basically, if you want to
make a wire, you take metal and draw it through a mold that has a hole in it.  You might
do this several times to get the gauge of wire that you want, but you can technically
make the mold any shape that you want.  The thing is that you have to remember that most
types of wires fill a specific purpose.  For example, wire is commonly made for
necklaces and is more comfortable than square wire would be (because of the edges) on
the skin.  Wire for dental braces is the same way.

If you
are talking more about electrical wiring, I can think of two reasons.  First, a lot of
electrical wiring is not a solid piece of metal but is really made up of many, many tiny
threads of wire twisted together.  This makes the wires more flexible, and round wires
are better for this purpose because they will fit more closely together (unless somebody
takes the time to stack each square wire properly against each-other.)  Secondly, when a
wire is threaded through wood or a hole in the wall the hole has usually been made by a
drill with a round bit.  The wire will go much more easily through a hole in the wall
that is round if it is indeed round as well.  Just think of that goofy toy we used to
play with as babies with the round holes and the square
pegs.

Hope this helped!