Dwight Eisenhower inaugurated the US. Interstate System, which now boasts more than 50,000 miles of roads. The idea came to a young Eisenhower in 1919 when he spent 62 days with a military convoy snaking across America on its primitive road system. But the idea for a trans-continental road network go back much further than Eisenhower. George Washington talked of the need for a vast system of roads to stitch together the nation.

But the true genesis of the U.S. Interstate system is the Roman Empire's road network. The empire in the first century constructed a network of 50,000 miles of paved roads, connecting its capital to the farthest-flung provinces. This fostered trade and commerce but most importantly allowed the Roman army to march quickly. The United States built its network for largely the same reasons.

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