US retail sales fell slightly in May amid supply-chain holdups that limited purchasing, the National Retail Federation (NRF) said.

Revenue slipped 1.3% month on month but rose 28% compared to the same period last year, reflecting coronavirus-related store closures during May 2020, according to data the US Census Bureau reported Tuesday. By contrast, April saw a 0.9% month-on-month increase.

The drop is the result of a logistics jam that has created a backup in retail orders, rather than lower demand, the NRF explained.

“While May retail sales were down slightly, largely due to supply-chain constraints, the more accurate indicator remains in the year-over-year data,” said NRF CEO Matthew Shay. “For the first five months of this year, retail sales are already tracking 17.6% above the same five months of 2020. While there are downside risks related to labor shortages, supply chain bottlenecks, tax increases and overregulation, overall, households are healthier, and consumers are demonstrating their ability and willingness to spend.”

Sales increased year on year in eight of the nine categories the US Census Bureau monitors. The clothing and accessories segment — which includes jewelry — was up 199%. Revenues for the category also rose 3% versus April.

Sales have grown year on year every month since June 2020, according to the Census Bureau. The NRF believes sales will continue to advance. Last week, it raised its outlook for the full year to reflect an expected year-on-year increase in retail sales of 10.5% to 13.5% to between $4.44 trillion and $4.56 trillion.