CDT stands for central daylight timing. According to CDT, it is required by the people of certain areas to move their clocks ahead one hour on 2nd November of each year and roll it back again on the second Sunday of the month of March. The reason that the law of CDT is being followed is that in 1966, it was Lyndon Johnson, then president of USA who finally signed the contract named Uniform time act and turned it into a specific law that is to be followed at all times.
The fundamental idea behind central daylight timing and its turning into a law is to be able to get the most out of the daylight hours and save as much of energy as possible. However, couple of reports, some of which may have published rather recently have reported that a significant change in the consumption of energy is never acquired by the use of central daylight timings. This is exactly why there has been a long debate in the utilization of CDT in USA and the potential benefits that it can provide. Since not a lot of reports have favored the benefits that it supposedly has to offer, it has been difficult lately to CDT as a law in USA. Nonetheless, as of now, CDT is still being followed in all parts of USA as a law that is not to be disobeyed.
It is indispensable to mention here that if you would like to get rid of the central daylight timings, Arizona and Hawaii are the only states within Unites States of America which do not follow the law of CDT. Getting established in these states will be your best bet if you want to get rid of moving your clocks forward or backward every year in particular months.