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Road Building
Good moning,everyone. Today Il be talking about the relationship between wad building and the devekpnent ofthe American eoononty durnu the 18th century. About 340) vears ainx the Unitex Statedcconony was wowing apidly, mainly becau of a booing tade in tvo important agricultural products gan and cotkon.
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allen什么意思Grain output in the castem part of America incread quickly at that time due to the rapidly gowing population and the large mumber of immigrants fion Europe. As a result, the demand for gain almost doubled. For this rcason, the trade in grain first devekoped in this part ofthe country. At the same tine, the rond system was gadually built up in order to transport the gmin fiom the numl arcas to various citics. The road building clearly helped devekop the cconony quickly in thess arcas and in the cities as wel
During the same perod,finters in the South couki gel a largee amoumt of aborers fon Aric, a
nd they started to aow cotton As the cotton output incrcasod, the fanmees needed to ll it in other phiwes.As a esull, many nuuds were buill tko link the rumal areas to the cilies.
At fist,this tade of grain and cotton tock plnce along the cosst, or near rivers and lalkes. It took place there becau it was casy and cheap to transport goods fiom one place tt another. Before 1700 it was very expensive to move the goocs by nad. So, terners had to rely manty on tivers to mo their crops to markets.
At that time, there was only one contingous road that existod in the US. It ran from north to south aong country toads which were linked together to make one long road. Within a short time the finst enst-to-west roas were buill. They were called tempikes Private comparnes built the roads and collected fees fiom all vehicles that taveled on them.
Evenlually,becau ofthe bonning trnie of wain and colon, a nelwork of rowys was completed that conpected some major cities and towns. Akhough taveling was still costly for lartners,they oon prefened to neve their crsps bo cilies and other aress on roklwys rather than by boat becau it was aster and more convenient
Soheee we can soe a lather clear picture of roed buildine in the Unied States and its inpact on cconomic development during that peridd.
The Mississippi River in America
Good afternoon. Today we're going to tak about the Mississippi River. The Missssppi River is the larst river of the North America. Its major tributaries drain an aren of approximately 3,000,000 squnre kilometers. or about one-eighth of the entire continent, The Missssppi River lies entirely in the United States. From its source at lake Itasca in Minncsota. it floys fom the North almost duc south across the continenta interior, collecting the waters of its major tributaries, down to the Gulf of Mexico.TheMighty Mssissippi as it is aflectionately known, flows a total distance about 4.000 kilometers from its source. With its tributarics, the M iss iss ppi drains all or part of31 U.s. state s arki two Canadin pro vinces
As everyone knows, in the past the river was the most important way of transporting goods from the North to the South, or from the South to the North in the United States
stand by>the touristThe Mississinoi River is also a river that con somctimcs ect out o feontro] and causc rious flooding in summer. Nowadays engineers u fbour different methods to control the loodwaters ofthe river. The lour ways are: food ways,dams, levees and rervoirs. Tu discuss each ofthe here.
bonerFloodways are the first way of controlling the foodwaters of the Mississippi River Foodways are empty channels ready to hold water from the river. When the Mississippi River is too high, the floodways are opened and some of the water can flow into the floodways. There are veral floodways along the lower Mississippi River, which help prevent flooding effectively
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The scoond way of controlling the floodwaters of the Mississippi River is with dams. Dams are walls that are bult across a river to control the water. There are more than 30 dams on the Miss issinpi River. Dams conttol the water by hokding the water behind them until a decision is made to relea it.
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Levees are a third way ofcontro lling the floodwaters of the Missssippi River. Levees are
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earthen walls built alongside a river. They bold the water in the river and keep it fiom covering the land beside the river. There are morc than 2,000 miles of levecs along the Mississippi River.
In the 19th and 20th centuries, veral rervoirs were but along the Mussissippi River to harness the water. They have two functions.One is to bold water, and tbe other is lo generale electricity through hydroelectric power stations. Since the 20th century, no huge flood has broken out oftbe Mississippi River.m
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