题目内容：
The Conquest of Distance1 In 1848,pioneers who crossed the American continent in their wagons made the trip in 109 days. Today a New York family can drive by automobile to San Francisco in less than a week or make the trip in several days by train, or fly there in five hours. The transportation has conquered the vastness of the land and brought together people living thousands of kilometers apart,
2 Railroads played a major role in uniting the far reaches of the continent. In 1830 there were only 37 kilometers of railroad track in the United States. But by 1863, two companies proposed to connect the east and west coast by a railroad all the way across the continent. Advancing eastward from California, the Central Pacific pushed forward across the desert；the Union Pacific moved slowly westward over the mountain plateaus. Finally, in 1869, the tracks of the two railroads met, and the first transcontinental railroad--the first real link between east and west－was completed.
3 Although the railroads brought towns and cities together, they could not go everywhere. In many parts of America, distances are so great that automobiles are necessities, not luxuries. As we have noted, most American farmers do not live in villages but are sometimes kilometers from their nearest neighbor and even hundreds of kilometers from a town. Large-scale farming is common in many parts of the United States today, but it did not become profitable until there were trucks and tractors. Trucks and cars go wherever there is a road and the more than six million kilometers of roads bring every field and barn into the circle of civilization.
4 The family automobile has helped to bring people of the United States two other things-two things which can seldom exist at the same time: community life and the privilege of privacy. In the early days of industrialization, factory workers lived close together, within walking distance of their jobs. As industries grew, more and more working class families lived together in crowded conditions. But with the construction of longer and better roads and with the greater availability of automobiles and other means of rapid transportation, it was no longer to live close to the factory. New residential areas, suburbs, grew up outside the big cities and, increasingly, industry and commerce concentrated in the cities. Every morning, millions of Americans dive their automobiles to work in the city, sometimes a distance of around 100 kilometers. At night they drive home to houses and apartments outside the cities, surrounded by trees and lawns.
5 Automobiles and other methods of rapid transportation are also changing American industry. Instead of continuing to concentrate in the big cities, industry is building factories in previously undeveloped areas. Because the means of transportation are available, it is not hard to transport people as well as materials to the places where they are needed. This factor was largely responsible for the
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