The northern parts of the United States get very cold in the winter. It snows a great deal and the temperature often goes 【C1】______ zero degree in January, 【C2】______ and March. But the northeastern and northcentral regions of 【C3】______ have been financial and industrial centers, and they are heavily polluted. In recent years, people in these regions have begun to take vacations 【C4】______ these cold winter months. They go to southern parts of the country 【C5】______ it is warmer. Many go to Florida where the weather is 【C6】______. Others go to the southwestern states of Arizona, New Mexico and Texas where they 【C7】______ dry desert climates. It has become 【C8】______ nowadays for old people to move south to these places 【C9】______ they retire. Typically these people sell their houses in their home communities and move south to begin a new life 【C10】______ senior citizens. Their children likely have homes 【C11】______ and many of them are moving south 【C12】______ communities where they were 【C13】______. The southern and southwestern parts of the country are now growing 【C14】______ any other part. Business and industry 【C15】_____ many offices and factories in the south. California is already the most popular state in the country.【C13】