It was quite a change for a man US had shunned for nearly a decade over his alleged role in the 2002 Gujarat riots under his watch as chief minister to have four US Senators, 36 House members and one state governor in the audience.
Besides meeting them individually backstage before starting his speech, Modi also sat down separately for nearly 15 minutes with Robert Menendez, Democratic chairman of the crucial Senate Foreign Relations Committee.
Ami Bera, the first US lawmaker from Modi's home state of Gujarat, said in a statement:"I am excited for America to realise the full potential of our relationship with India."
"Today was a key step toward what I believe can be a defining relationship of the 21st century between the US and India."
"The world's oldest democracy, and the world's largest democracy share many key interests, including growing our economies and ensuring stability in South Asia," he said.
Thanking Modi "for his inspirational words and for the vision he laid out," Bera said he looked "forward to continuing to work together to reinvigorate the US- India relationship."
Tulsi Gabbard, the first Hindu US lawmaker, said "Modi's visit marks a significant positive step toward growing the relationship between the US and India, which is a bond based on shared democratic values and a focus on mutual prosperity and security."
Gabbard, who will also attend a lunch hosted by Vice President Joe Biden and Secretary of State John Kerry Tuesday in honour of Modi Tuesday, said she expected the Indian leader "will continue to build the strong ties between our two great nations" in Washington too.
The Democratic lawmaker from Hawaii also thanked Modi for "sharing his inspiring message of his vision for a brighter future," and wished "him well as he works to carry out his mission of service."
Grace Meng, a Democratic member of the House Foreign Affairs Committee and the Congressional Caucus on India and Indian-Americans, who also "attended the historic event" at Madison Square Garden, called it "a homerun."
"He hit all the right themes, highlighted all the right issues, and brought the US-India relationship to a new high," she said.
"In his robust agenda, he correctly highlighted the strength of India's democracy, its workforce and the importance of education and development," Meng said.
"He also hit the nail on the head by seeking to boost tourism, addressing inequity, invoking the legacy of Mahatma Gandhi and touting the success of the Mars Orbiter Mission.
"There is no doubt that his address will further increase India's influence on the world stage, and improve prosperity for both our countries," she said.