In the US power transmission is three phase at high voltage (which is where voltage drop is really a big concern). Voltage drop within a building is rarely a concern in the vast majority of buildings.
Typical electrical service for small buildings is 240v using two of the three legs. At the service panel each of the legs is available separately as 120v or in combination as 240v. Larger buildings and industrial applications will often use 208v three phase services for power efficiency. Higher 3 phase voltages are also used on a more limited bases
Actually, at least in Sweden, 3-phase 380/400V is available in most homes for power-hungry things like electric stoves, water heaters, etc. I've never seen this in the U.S, so combined with the lower voltage, you need really thick wires to support the 20+A you need to run a 2500W stove. Seems like a waste of copper. I wonder if the U.S. resistive losses are noticeably larger than in Europe. Certainly you notice extension cords for things like vacuum cleaners get very warm in the U.S.
Ranges are 240V and 50 Amps; clothes dryers are 240 V and 30 Amps. Both have 3 prong plugs that are much larger than 120 V outlets, the dryer plug has an L-shaped prong so it can't be inserted into a range outlet. (The reason you don't want the dryer plugged into a range outlet, is the internal wiring is inadequate for 50 amp loads, and can burn out without tripping the 50 amp breaker on range circuits.)
This is not fully correct, there is such a service as 'single phase' and that is what most US residential service consists of, where the transformers that step down line voltage at the pole, or in an underground vault to 2 separate legs of power, that are 240v differential between them, and 120v from a neutral that is derived at the transformer.
If you were to take the 3 phase power more common in large buildings, or light industrial facilities, and use any two legs, you would be looking at 208v between any 2 legs, and 120v between any leg and the neutral from the step down transformer.
Almost any variant of power can be produced by the correct transformer, given the the basic power available to location is sufficient, and of the correct type (i.e. 480v 3 phase can be tranformed into 208/120v 3phase or 240/120v single phase).
This is also the case in Europe just with different numbers. There are three 230V legs, each within 120 degrees of phase difference from each other. If two are combined, you get 230V * (sin 60) * 2 = 400V which can be used for industrial applications.
Not quite - the US has a unique split neutral where an incoming 240V single phase is divided into +/- 120V to drive either 120V to earth or 240V heavy duty appliances. But the dryer supply in the US isn't a multi phase
That is the single phase that is common in most residential service in the US. It is separate from the 3 phase service you find in light industrial and large office buildings.
Typical electrical service for small buildings is 240v using two of the three legs. At the service panel each of the legs is available separately as 120v or in combination as 240v. Larger buildings and industrial applications will often use 208v three phase services for power efficiency. Higher 3 phase voltages are also used on a more limited bases