4 Min Read WASHINGTON (Reuters) - High-frequency measures of the U.S. economy may be showing the first signs of an expected spring revival, with employment at small and medium-sized businesses rising slightly, and traffic to retail stores improving from the levels of last fall when the coronavirus surged. FILE PHOTO: People dance to live music at Mattison's City Grille, as the coronavirus disease (COVID-19) pandemic continues, in Sarasota, Florida, February 10, 2021. REUTERS/Shannon Stapleton/File Photo The challenges facing the U.S. economy remain mountainous. Nearly 800,000 people filed for unemployment insurance in the week ended Feb. 6, and as of late January more than 20 million were collecting some form of unemployment benefit - 10 times the typical level.