SIOUX CITY—The U.S. Postal Service says it is again reviewing whether to consolidate its Sioux City processing center with one 75 miles north in Sioux Falls, S.D. The service decided against doing so five years ago, when the idea was first raised. There’s been a substantial drop in first-class mail revenue since, thanks in part to web-based bill paying. The Postal Service lost $8.5 billion in the year ending Sept. 30 and estimates it will lose $6 billion to $7 billion in the next year. Postal Service Spokesman Richard Watkins says that postal customers wouldn’t notice any change and that Sioux City would keep its postmark. A consolidation study is expected to be finished before fall.