U.S. Route 30 in Iowa runs generally east–west for 330 miles (530 km), and is the longest primary highway in Iowa. Going east, US 30 enters Iowa at the Missouri River bridge from Blair, Nebraska, and exits at Clinton, crossing the Mississippi River. The highway runs close to the Union Pacific Railroad's Overland Route as both cross Iowa. US 30 was conceived as a part of the Lincoln Highway, the first transcontinental highway in the United States. A route through Iowa was chosen because of the important link between Omaha, Nebraska, and Chicago, Illinois, and, by 1931, it had been paved across the entire state. US 30 originally passed through many small Iowa towns, but over time, the route has been straightened, bypassing most downtown areas, and with long sections upgraded to a four-lane expressway. Since 2006, US 30 has been designated an Iowa Heritage Byway, the first highway in the state with that distinction. (Full article...)