In an effort to increase efficiency, package delivery company UPS is reducing services in some rural areas, according to industry reports.

UPS said that shipments in certain ZIP codes will spend an additional day in transit through its new initiative, according to Supply Chain Dive. The delivery company said its UPS Premier service would continue to guarantee delivery dates, and that critical healthcare deliveries would not be affected.

“This affects less than one percent of our deliveries every day, so the vast majority of our customers will not experience any difference in the service they receive,” UPS said, according to reports. “We are constantly evaluating and modifying our network, and we remain committed to providing our customers with the most reliable and efficient service wherever they live and work.”

The company did not specify which ZIP codes will be affected. However, Supply Chain Dive cited multiple local news reports from areas have seen changes in service.

“Areas impacted by the change this year have included the Key Peninsula area in Washington state, some smaller cities in Middle Georgia, a handful of towns in Piscataquis County, Maine, communities surrounding Mobridge, South Dakota, and rural West River communities in South Dakota,” Supply Chain Dive reported.

Last month, the Federal Aviation Administration announced that UPS would be allowed to expand its use of drone deliveries.

In July, the company announced that a new five-year contract had been reached with UPS’s 340,000-member union, averting a nationwide strike.