Key airports and railway stations in Japan's major urban areas became congested with travelers Thursday as the annual rush of summer holidaymakers got into full swing.

A number of domestic flights from Haneda airport in Tokyo, notably those bound for the northern main island of Hokkaido and southern islands in Okinawa, were fully booked while almost all reserved seats on westbound Shinkansen bullet trains leaving Tokyo Station were full throughout the day.

The international hub airports of Narita near Tokyo and Kansai, located south of central Osaka, were packed with people going on overseas trips during the peak holiday period from Thursday through Aug. 20.

About 55,600 people are expected to leave for foreign destinations on Thursday, according to the operator of Narita airport. It also estimates the total number of travelers, both outbound and inbound, at nearly 1.07 million with peak departure numbers coming on Friday and arrivals on Aug. 20.

Officials at Kansai airport say about 728,500 passengers are likely to travel on international flights during the 11-day period, including 35,100 who are expected to leave on Thursday alone.

Friday will most likely be the peak day for people traveling to internal Japan destinations by rail or on expressways. For return trips, congestion is expected to be spread over several days.