The number of visitors from the US soared by more than 16% during the spring months, it has emerged.
Official figures show 207,000 holidaymakers travelled to Ireland from the US between February and April, up from the same time last year.
Trips by residents of Great Britain fell by 2.2% to 638,600, while numbers from mainland Europe grew by 8.8% to 541,500.
Niall Gibbons, chief executive of Tourism Ireland, said the figures show an overall growth of 4% and suggest a positive start to 2013 ahead of the busy summer months.
"I particularly welcome the increase in visitor numbers from north America, which suggests we could be on course to achieve our best year ever from that market," he said. "In 2013, we hope to welcome over one million American visitors, spending about 1 billion US dollars."
The Central Statistics Office (CSO) revealed almost 1.5 million trips were made to Ireland over the three months, compared to the 1.33 million holidays that Irish people took overseas. It showed the numbers of visitors to Ireland from around the world outside America and Europe fell by 2.8% to 70,000.
Mr Gibbons said tourism has a critical role to play in contributing to Ireland's economic recovery, accounting for 59% - approximately 3.5 billion euro - of all tourism revenue. He believes mainland Europe holds the key to tourism growth.
"It is very encouraging to see strong performances for the February to April period from important European markets like France (+20%), the Nordic region (+15.3%), Germany (+4.5%) and Benelux (+9%)," he added.
"We know that Great Britain continues to be challenging, with the pace of economic recovery and weak consumer confidence still continuing to impact on outbound travel. We are implementing our "GB Path to Growth" plan, developed in conjunction with industry partners, to return this - our largest - market to sustained growth."
Tourism Minister Leo Varadkar said the figures show the Gathering 2013 is picking up pace with the growth encouraging ahead of the main tourist season. "Visitor numbers from mainland Europe performed particularly well, showing the strongest performance since 2007, while North America generated the highest number of arrivals in over a decade," he said.