The United States government receives an enormous number of immigration applications every year. In fact, they receive more applications that there are available visas. To address this issue, around 80,000 applications are randomly selected through a lottery process each year that is held in early April.
However, there is another step to the lottery process that involves the winners going through additional evaluation from U.S. Citizenship and Immigration Services (USCIS) before they can legally work in the United States. This is where significant immigration delays often crop up.
It is not unheard of for premium processing to be delayed for a few weeks every year so USCIS employees can deal with the influx of applications. Suspensions can last up to six months, if not longer.