This paper explores the role of geographical expansion of railroads,one of the most important Fransporta-tion vehicles,in the history of American west development,analyses its implication on the unprecedented mi gration move-ment and the resulted urbanization i n the west and concludes with the fact that the appropriate interference b y the governm-net,especially in the early period,is vital to regional development pra ctice,because of market failure at t he initial stage,infrastructure constructio n conducted by the government always plays as the first impetus to any regional develop-ment process.Only through this brid ge,can some physical factors,such a s population,be attracted to feed th e back-ward area.As a result,cities grow fa st and the region develops well.The e xperience can be shared by all countr ies.Be-sides reviewing the history of west development in America,focusing on t he relationship between railroads e xpansion and urban growth,which was realized thr ough population migration.Acomparison on the particular pattern of regional develop-ment between U.S and China is made as well at the end.It is noted that despite of the common first impetus,govern-ment subsidies and the common final r esult,urbanization,the path for th e America is bottom-up,whereas that for China is top down,that is to say,developme nt should originate from big cities,then to towns,and finally radiate in to rural ar-eas. This paper explores the role of geographical expansion of railroads, one of the most important Fransporta-tion vehicles, in the history of American west development, analyzes its implication on the unprecedented mi gration move-ment and the driven urbanization in the west and concludes with the fact that the appropriate interference by the governm-net, especially in the early period, is vital to regional development pra ctice, because of market failure at t initial stage, infrastructure constructio n conducted by the government as plays the first impetus to any regional develop-ment process. Notably through this brid ge, can some physical factors, such as population, be attracted to feed th e back-ward area. As a result, cities grow fa st and the region develops well. The e xperience can be shared by all councils ies.Be-sides reviewing the history of west development in America, focusing on t he relationship between railroads e xpansion and urban growth, which was realized thr ough populatio n migration. A comparison on the particular pattern of regional development-mentality between US and China is made as well at the end. It is noted that despite the common first impetus, govern-ment subsidies and the common final r esult, urbanization, the path for th e America is bottom-up, then that for China is top down, that is to say, developme nt should originate from big cities, then to towns, and finally radiate in to rural ar-eas.