The USA is comprised of 50 states and a federal district (Washington DC). The part of the country located south of Canada is referred to in any different ways, such as the "lower 48", the "mainland" or the 48 "contiguous states".
There are several quasi-autonomous dependencies belonging to the USA. Some of these are very well known, such as Puerto Rico, Virgin Islands and Guam and then there are some that even Americans may not know about, such as Baker Island, Johnston Atoll and the Northern Mariana Islands.
Time zones
There are 4 time zones in the "lower 48" and these are: EST, CST, MST and PST. They stand for Eastern, Central, Mountain and Pacific Time Zones, respectively. Alaska has its own time zone, one hour behind PST, and Hawaii is 2 hours behind PST.
EST is 5 hours behind GMT and PST is 8 hours behind.
Daylight savings time starts on the second Sunday in March and ends on the first
Sunday in November. This is slightly out of sync with Daylight savings in Europe.
Extremes in USA geography
Given its location as being in the middle of the continent, the USA has the luxury of having some very desirable climates and landscapes. From the subtropical Hawaii to Arctic Alaska, all climates in-between can be found, as can most landscapes.
The tallest mountain is Mt McKinley (20,320 feet / 6,194 meters) in Alaska and the lowest elevation is Badwater Basin in California sitting at -282 feet / -86 meters below sea level.