After residing in the United States as a permanent resident for five or more years, the next step that a person normally takes is filing Form N-400, Application for Naturalization, to become a naturalized US citizen. It is well known that a permanent resident is granted various rights in the United States. However, there are a few restrictions and limitations; as a permanent resident may not travel to a foreign country for an extended period of time and is not given the right to vote. Whereas US citizenship does not restrict them from traveling and does not prevent them from voting in the federal elections.
In order to enjoy full economic and political membership in the society, a permanent resident can become a US citizen. On becoming a naturalized American citizen, a permanent resident will be granted all the rights that are conferred to natural born US citizens. At this point, a foreign national who becomes a US citizen will be also be able to vote in the federal elections. Moreover, an immigrant who becomes a citizen of the United States will not be deported from the country for any reason and can find jobs anywhere in the country.
Similarly, US citizens may not have any limitations towards traveling abroad. The other important benefit that the US citizens will get is a US passport, and it must be remembered that US passports are granted only to US citizens and permanent residents may not get US passports. You may sponsor only your spouse and children if you are a Green Card holder, but you will be capable of sponsoring few other categories of relatives, after you become a citizen of the United States.
It is not mandatory to become a US citizen, and the US immigration law allows an immigrant to be a permanent resident forever. But US citizenship is considered to be an important milestone in the journey of an immigrant. It is however, not a simple task to obtain US citizenship. A permanent resident will have to meet a variety of eligibility requirements such as residency requirements and must establish that he is well aware about the US laws and history and must prove that he is good in the English language. And to prove that, he must pass the naturalization test which consists of two parts, the English component and the civics component. Background security checks are also a part of the naturalization process. On satisfying all the requirements and after getting through the citizenship tests, USCIS will allow the permanent resident to take the oath of Allegiance and will grant a naturalization certificate. Henceforth, the person may remain in the country as a US citizen.
Some Green Card holders do not choose to become US citizens, as some of them lack motivation and few of them are not aware of the rights and the benefits of becoming US citizens. Some immigrants who earn less are discouraged because of the fee that they have to pay while applying for naturalization. They are also unaware that they can request a fee waiver.
Naturalized US citizens need not hold Green Cards and renew those cards every year, which also costs them a lot. Hence, the best option is US citizenship which does not require you to remember any renewal dates. You may enjoy a lot of economic and political benefits and you will be free to travel around the country, if you become a citizen of America through naturalization.