Iowa’s seasonally adjusted unemployment rate remained at 2.4 percent in December, Iowa Workforce Development said in a release. The state’s jobless rate was 2.9 percent one year ago. The U.S. unemployment rate rose to 3.9 percent in December. The number of unemployed Iowans remained at 40,600 in December. The current estimate is 8,700 lower than the year-ago level of 49,300. The total number of working Iowans increased to 1,651,300 in December. This figure was 2,300 higher than November and 25,700 higher than one year ago.