A key monthly index of U.S. shipping activity reported modest sequential improvement in November, giving rise to hopes the three-year freight recession may be coming to an end.

The index, published by freight audit and payment firm Cass Information Systems, is based on the expenditures and shipments of Cass's clients. In November, the freight expenditure index came in at 1.596, up from 1.51 in October and 1.55 in September. The shipment index came in at 0.947, up from 0.921 in October but still below the 0.966 reported in September, Cass said.

Since the start of 2009, the Cass index has fluctuated wildly. Shipment activity in February was ahead of January levels. The index then declined in March and April, increased in May and June, and declined in July, only to increase again in the next two months.

In a sobering reminder of how volumes have declined since 2006 and 2007, the shipment index was consistently in the 1.2 to 1.3 range during those two years, according to Cass data. The index has not exceeded 1.0 since November 2008.

In 2008, Cass audited about 26 million shipments representing roughly $17.5 billion in shipper expenditures.