Correction:

The speed of electron flow in a conductor is more like a few feet per
hour rather than a few miles per hour as I said, at reasonable current
levels and wire sizes (but depending on the current and the wire
diameter). The numerical example for copper shown at the web site I
mentioned shows an electron drift velocity of 4.3 mm/s for a 1 mm
diameter wire with 46 A current (which would probably explode the wire).
This works out to about 51 feet/hour. At the more reasonable current of
3 A, the electron drift velocity drops to 0.28 mm/s, or about 3.3 feet/hour.

The electron drift velocity is so slow because, even though an ampere of
current is a seemingly staggering 6 X 10^18 electron charges per second,
there are vastly more free electrons than this in even a small wire.
(Again see the web site example, where the density is shown to be about
8.5 X 10^28 electrons/m^3, or about 6.7 X 10^22 electrons in the 1 mm
diameter, 1 meter long wire in the example.)(*) Carefully using the
drinking straw analogy again, imagine a very large diameter drinking
straw (lots of free water "electrons"), where an ampere of current is
represented by a tiny trickle of water. If you suck water out one end at
the rate of "one ampere", it takes a long time for the actual water
molecules at the other end of the straw to work their way up the straw.

(*) You can, in fact, calculate the drift velocity somewhat more simply
and perhaps more intuituvely than the author of that page did, knowing
only the electron density and the size of the wire. From the wire size
you can calculate its volume as 7.85 X 10^-7 m^3. Multiplying this by
the electron density, you get the total number of free electrons it
contains, about 6.7 X 10^22. So the wire holds 6.7 X 10^22 / 6 X 10^18 ~
11,000 coulombs (ampere-seconds) of available charge. If we move charge
through at the rate of 46 amperes as in the first example, it would take
11,000/46 ~ 240 seconds for an electron to move from one end of the wire
to the other, a rate of one meter/240 seconds or about 4.2 mm/sec.
Within roundoff error, this is what the author calculated.

Roy Lewallen, W7EL

Roy Lewallen wrote:

. . .
In a wire, for example, charge
flows much faster (near the speed of light) than electrons (which flow
at a rate on the order of a few miles per hour). . .
. . .

-- A quick web search brought this brief explanation of how electrons
behave in a conductor:
http://hyperphysics.phy-astr.gsu.edu...ic/ohmmic.html. . .