Relations between Boston, Massachusetts, United States and Halifax, Nova Scotia, Canada date back to the founding of Halifax in 1749, when Boston businesses had an interest in the new settlement for shipping and fish trade. The bond between the two cities became stronger following the Halifax Explosion in 1917, after Boston sent significant aid and disaster relief to Halifax. Boston is the capital of Massachusetts, Boston is the most populous city in the multi-state region New England, and Massachusetts is the most populous state in New England. Likewise, Halifax is the capital of Nova Scotia, Halifax is the most populous city in the multi-province region Atlantic Canada, and Nova Scotia is the most populous province in Atlantic Canada. New England and Atlantic Canada border each other by land and sea along the Canada–United States border. Boston and Halifax are both are major port cities on the Atlantic Ocean. Halifax Explosion On December 6, 1917 at 9:04.35 AM, the Halifax Explosion severely destroyed much of the city. Boston authorities learned of the disaster via telegraph, and quickly organized and dispatched a relief train around 10:00 PM that night, to assist survivors. A blizzard following the explosion delayed the train, which finally arrived in the early morning on December 8, and immediately began distributing food, water, and medical supplies. Many personnel on the train were able to relieve the Nova Scotia medical staff, most of whom had worked without rest since the explosion occurred. Christmas Tree tradition In 1918, Halifax sent a Christmas tree to the City of Boston in thanks and remembrance for the help that the Boston Red Cross and the Massachusetts Public Safety Committee had provided immediately after the disaster. That gift was revived in 1971 by the Lunenburg County Christmas Tree Producers Association, who began an annual donation of a large tree to promote Christmas tree exports as well as to acknowledge Boston's support after the explosion. The gift was later taken over by the Nova Scotia Government to continue the goodwill gesture as well as to promote trade and tourism. The tree is Boston's official Christmas tree and is lit on Boston Common throughout the holiday season. Knowing its symbolic importance to both cities, the Nova Scotia Department of Natural Resources has specific guidelines for selecting the tree. It must be an attractive balsam fir, white spruce or red spruce, tall, healthy with good colour, medium to