The event is also expected to be attended by a number of US lawmakers.
Held under the banner of newly-formed "Indian American Community Foundation", Modi is expected to deliver a major policy speech on Indian Diaspora from the historic Madison Square Garden in the New York City on September 28.
An official announcement is yet to be made.
Given that the Madison Square Garden in Midtown Manhattan in the Big Apple, having a capacity of 18,000 to 20,000 people, is expected to be jam packed, this would be the largest ever public address by an Indian Prime Minister, or for that matter an Indian leader overseas.
And given that even mainstream a politicians have a tough time in attracting a few thousand people to their events, Modi addressing nearly 20,000 people at one venue on September 28, would be considered as a massive rally by American standards.
To mark this occasion, community leaders are inviting their Congressmen to attend what they are building as "a historic reception" for a foreign leader on American soil.
A large number of US lawmakers are expected to attend the event.
Ram Madhav, the newly appointed BJP national general secretary, was in Washington and New York this week holding meetings with the community leaders to have an on-the-ground assessment of the preparations.
After the civilian nuclear-deal, this is for the first time such a large number of Indian American organizations have come together on a platform.
