This paper presents the results of a new survey of lexical variation in North American English, called the North American Regional Vocabulary Survey(NARVS). Apart from introducing many new variables that have not been previously studied, the paper examines the use of two quantitative methods,net variation and major isoglosses, as ways of distinguishing the most important regional lexical divisions and the most powerful lexical variables from regional divisions and variables of lesser importance. The quantitative analysis motivates several conclusions. English-speaking Canada is shown to comprise six principal lexical regions:the West, Ontario, Montreal, New Brunswick-Nova Scotia, Prince Edward Island,and Newfoundland. A list of the most powerful variables for distinguishing Canadian regions is presented, headed by the set of regional terms for a`house in the country where people go on summer weekends' (cabin,cottage, etc.). A similar analysis of lexical differences across the Canada-United States border is developed, which concludes that no region of Canada can be reliably distinguished as relatively more American than any other and that Canadian regions have more in common at the lexical level with each other than any of them has with the United States.