By the 16th century, the city's trades and craftsmen had begun to wield significant influence, particularly the Incorporation of Tailors, which in 1604 was the largest guild in Glasgow; the merchant and craft guilds accounted for about 10% of the population by the 17th century.[8] With the discovery of the New World and the trade routes it opened up, Glasgow was ideally placed to become an important trading centre with the Clyde providing access to the city and the rest of Scotland for merchant shipping. Its path to success was not to be easy, however: in 1651, the English Navigation Acts were passed, making it illegal for non-English ships to trade with English colonies.