Sinn Fein has raked in over $390,000 in donations from US donors in just six months.
The party is building a massive financial war chest from wealthy donors, trade unions and major companies.
According to documents released by the US Department of Justice, Sinn Féin received dozens of individual donations ranging from $10-$20,000.
Gerry Adams's party is unrivalled in its capacity to generate huge sums of cash in the US.
In one instance, the party was left more than $1,000 dollars as part of the estate of a deceased person.
But the largest individual donation of $20,000 was provided by the New York-based engineering firm United Structural Works.
An $11,000 donation was made by the New Jersey-based McGuigan Tombs & Company, which specialises in tax consultancy.
Two donations of $10,000 were made by the Eurotech Construction Company and a Chicago-based individual listed in the documents as Tom Moran.
The extraordinary cash pile lies in five bank accounts based in New York, which are operated by the Friends of Sinn Féin (FSOF) organisation.
FSOF is headed by Jim Cullen - a former US army general whose parents are Irish.
The party told the Irish Independent that the money is not used in the Republic and cannot be used to help fund their election campaign.
Instead, it is channelled into Northern Ireland where it finances party operations.
The documents, which were released this week, show that over $52,288 was used to pay for advertising, legal and printing expenses in the North.
The donations are detailed in accounts given to the US Justice Department under the Foreign Agents Registration Act. Under this act, all political parties based outside of the US must supply fundraising details to the US government.
In an interview earlier this year, James Cullen insisted that electoral rules preclude the party from using some of its fundraising amounts to fund its operations in the Republic.
"There is a three-member board, of which I am chairman, that ensures that we imitate Caesar's wife: we want to be sure that we are above reproach," Mr Cullen said.
Friends of Sinn Féin regularly stages events in US cities as part of the fundraising drive, which have resulted in millions of dollars being raised in recent years.
Senior party figures such as Mary Lou McDonald and Pearse Doherty have addressed such events in recent months.
The documents also detail an address made by Sinn Féin leader Gerry Adams at the annual Friends of Sinn Féin dinner in New York in November.
The Louth TD made light of a gun being placed to the head of the editor of the Irish Independent by volunteers associated with rebel leader Michael Collins.
His comments were widely condemned both at home and by international journalists groups.
Mr Adams has repeatedly rejected calls for him to withdraw the comments.
In a statement, a Sinn Féin spokesperson said the money raised is used to promote "the cause of Irish unity and the peace process".
"The role of Sinn Féin is to promote Irish unity, safeguard the peace process and deliver the type of republic envisaged in the proclamation; these aims are shared with those who support FOSF USA.
"FOSF USA is fully transparent and compliant with all USA laws and regulations. Both funds raised and spending are fully accountable and transparent... all of those who contribute to FOSF USA are doing so to demonstrate their support the cause of Irish unity and promote the republic envisaged in the proclamation."