New figures show Dublin Airport handled more than 3.1 million passengers in July.
The daa says this was a new monthly record, and a 6% increase on the same period last year.
This means more people used the airport in July than during all of 1986.
It was also the first time in the airport's 77-year history that more than three million passengers have been facilitated in a single month.
More than 16.9 million passengers have travelled through Dublin Airport in the first seven months of the year.
The number of passengers travelling to and from continental Europe increased by 7% to more than 1.7 million, which was a new high.
However UK traffic was flat compared to July last year, as almost 896,000 passengers took flights to and from the UK in June.
The number of the UK trips to Dublin fell during the month, but this was offset by an increase in the number of outbound trips to the UK.
Dublin Airport Terminal 2 departure gates | Image: daa
Transatlantic traffic increased by 18% in July to a new record, with more than 404,000 people travelling on flights between Dublin and North America last month.
Traffic on other international routes - which includes flights to the Middle East and North Africa - increased by 8% with more than 91,000 passengers travelling to and from these locations.
The number of passengers on domestic flights, increased by 22% with more than 10,000 people taking flights within the Republic of Ireland last month.
Dublin Airport managing-director, Vincent Harrison, said: "This is a major milestone for Dublin Airport and for the Irish economy.
"Growing passenger numbers means additional jobs at the airport, and at businesses throughout the country that benefit from growing tourism and additional trade and investment."
Dublin Airport supports or facilitates 117,300 jobs in the Irish economy.
Some 20,000 of those jobs have been created over the past four years and are linked to the growth in Dublin Airport's passenger numbers during that period.
"The record visitor numbers for the first half of this year are being driven by passenger growth at Dublin Airport, with the new routes and additional capacity provided by our airline partners facilitating the growth in tourists so far this year", Mr Harrison added.