Bundesliga club Borussia Dortmund have opened a third overseas office in New York City to boost their marketing activities in the American continent. Dortmund said on Friday that the opening took place the previous night, with 300 guests from the worlds of politics, business and sport in attendance at the One World Trade Centre. Dortmund’s other offices are in Shanghai and Singapore. The club has had several pre-season trips to the United States in the past and runs a training academy in Dallas. The US market is gaining in importance, with the new-look Club World Cup played there next year, an…