Today is Citizenship Day, a day that marks the adoption of the Constitution and celebrates U.S. citizenship. According to the United States Citizenship and Immigration Services, some 8.5 million green card holders are currently eligible for citizenship. Yet many don't apply. The process can be cumbersome and costly--but a new web tool seeks to make it easier.

The New Americans Campaign has created a database called Zip to Citizenship, which lists nearly 800 organizations that help with citizenship applications in every state. Green card holders simply enter their zip code and are then directed to a page of organizations that help with the process at little to no cost.