The first regular rail service for more than 50 years has begun operating across the heavily fortified border between North and South Korea.
The flower-strewn cargo train, carrying raw materials for an industrial zone, left South Korea early in the morning.
It will run 25km (16 miles) to Bongdong in the North before returning.
The service was agreed at an October summit between leaders of the Koreas, only the second since the peninsula was divided more than five decades ago.
Cargo trains will cross the border every week day, slashing the cost of transporting goods to and from the jointly run Kaesong industrial zone, just north of the border.
Several South Korean firms have bases in Kaesong, where they have access to cheaper labour.
Until now, trucks have been moving raw materials and finished goods back and forth across the border.
Lee Chul, president of Korea Railroad, said the economic benefits of the link were countless.
THE TWO KOREAS
1910: Korean Peninsula colonised by Japan
1945: Divided into US-backed South and Soviet-backed North
1950-1953: Korean War, no peace deal signed
1987: North Korea bombs a South airliner, killing 115
1990s: South Korea introduces conciliatory Sunshine Policy
2000: Kim Jong-il and Kim Dae-jung hold first leaders' summit
2007: Kim Jong-il and Roh Moo-hyun hold second leaders' summit
"Though we start with a cargo train, it will lead to a passenger train service and will soon be linked to the continental trains," he told journalists as the train left South Korea.
Seoul is seeking wider rail links with North Korea that would allow connections to China, Russia and beyond, but Pyongyang has so far opposed this.
It is also seeking regular cross-border passenger services.
"I'm happy to drive this train to the North where both my parents were born," said driver Shin Jang-chul. "I hope not only cargoes but tourists as well will use this train to go back and forth."
Rail lines between the two sides were severed during the 1950-53 Korean War. No peace deal was signed, meaning that North and South Korea remain technically at war.
But in recent years Seoul has pursued a policy of economic engagement with Pyongyang and worked to ease tensions.
Roads were reconnected following the first inter-Korean summit in 2000, and a second was held in Pyongyang in October.
There South Korean President Roh Moo-hyun and North Korean leader Kim Jong-il signed a wide-ranging accord calling for greater peace and economic partnership.
The rail service is the first concrete achievement to come out of the summit.