October 20, 2002: Concrete for new US 20 ends at the Grundy/Hardin county line, as seen from the B Avenue/Z Avenue bridge. A full gallery of that fall’s construction can be seen here.
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U.S. 20 between Sioux City and Moville will officially become a four-lane highway Monday morning with ribbon-cutting ceremonies on 13.3 miles of eastbound lanes.
— Sioux City Journal, November 14, 1964
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Iowa Highway Commission Chairman Derby Thompson promised Tuesday that improvement of U.S. 20 into a four-lane freeway across the state will have “top priority” in the state’s highway construction plan.
— Des Moines Register, November 4, 1970
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Bill Trampe, chairman of the Hardin County Conservation Board, one of the groups opposed to the completion of the project, said, “The conservation board will use every legal means available to stop the road going through the Iowa River Greenbelt.”
… Completion of Highway 20 from I-35 to Highway 65 is included in the DOT’s five-year plan, with projected completion in 1986-87. [It wasn’t. — Ed.]
— Waterloo Courier, July 15, 1983
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The new lanes of westbound U.S. 20 are scheduled to open between Correctionville and Holstein on Wednesday, October 17. A lane closure will be utilized in the eastbound lanes to restore the pavement markings.
— The most understated Iowa DOT mailing list release ever, October 15, 2018
The Des Moines Register has more,* including a timeline that uses dates from Jason Hancock’s website (and thus, my research from more than a decade ago).