????隨著2014年中期選舉越來越近，民主黨將把移民制度改革問題當(dāng)做突破口，以此向存在弱點(diǎn)的共和黨人施壓，迫使共和黨人要么激怒選民、支持移民制度改革，要么失去這個(gè)關(guān)鍵群體的人心。

????涉及移民有關(guān)的政治問題很復(fù)雜，經(jīng)濟(jì)問題也是如此。移民到底是不是降低了美國低技能勞動者的工資水平？研究者們對這個(gè)問題莫衷一是。但就其他問題而言，比如移民是否促進(jìn)了整體經(jīng)濟(jì)增長，數(shù)據(jù)一清二楚。移民絕對是經(jīng)濟(jì)增長的動力所在。

????要凸顯這一點(diǎn)，途徑之一是用過去30年美國的經(jīng)濟(jì)增長速度和法國、英國、日本等富裕國家進(jìn)行比較。人們經(jīng)常掛在嘴邊的一個(gè)事實(shí)是，差不多80年的經(jīng)濟(jì)數(shù)據(jù)顯示，美國的增長速度一直比其他國家快，原因是美國更熱衷于堅(jiān)持經(jīng)典的資本主義原則。大家可以看看下面這幅圖，顯示的是從1982年到2012年的名義GDP年度增長率（其中藍(lán)色曲線為美國，橙色為法國，紅色為英國，綠色為日本）：

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????As the 2014 midterm elections draw nearer, the issue of immigration reform will be used as a wedge to pressure vulnerable Republicans into either angering their base and supporting reform, or alienating key demographics.

????The politics of immigration are complicated, as are the economics. Researchers are split over whether immigration brings down the wages of low-skilled workers in the U.S. But with respect to other questions, like whether immigration promotes overall economic growth, the data is clear. It overwhelmingly does.

????One way to highlight this is to compare economic growth over the past 30 years in the U.S. to other wealthy countries like France, the U.K., and Japan. A stylized fact often thrown about is that the United States, over the 80 or so years in which we've measured this sort of thing, has consistently grown faster than other countries due to its more enthusiastic adherence to classic capitalistic principals. Check out the graph below, which shows nominal yearly GDP growth from 1982 to 2012:

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????如圖所示，美國的表現(xiàn)一直好于同類富裕國家。在這30年中，美國的平均名義GDP增長率為5.4%，法國為1.8%，英國和日本分別為2.4%和1.9%。

????但人們經(jīng)常忽略這樣一個(gè)事實(shí)，那就是和同類工業(yè)化國家相比，美國的人口增長率一直較高?，F(xiàn)在，讓我們再看一下這30年間的經(jīng)濟(jì)增速，衡量標(biāo)準(zhǔn)是人均GDP：

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????As you can see, the U.S. consistently beats out its wealthy peers. Over this period, nominal GDP growth in the U.S. has averaged 5.4%, compared with 1.8% in France, 2.4% in the U.K., and 1.9% in Japan.

????But one fact that often gets overlooked is that the U.S. population has been and continues to grow at a faster rate than its industrialized peers. Take a look now at GDP growth over that same period, this time on a per capita basis:

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