 This section was completed in October 1955 and would later become a portion of Interstate 80 in December 1973.The department's first Interstate project was a section of I-80 near Gretna that began in June 1957 and opened to traffic in November 1959, ushering in the era of Interstate Highway travel in Nebraska.The Interstate continued to be the focus of development throughout 1960s and 1970s with I-180 completed in 1964, I-76 in 1969, I-480 in 1970, I-80 in 1974, I-680 in 1975 and I-129 in 1977.