In an effort to cut costs and provide more reliable service, the United States Postal Service finalized a plan to slow down some of its mail delivery starting October 1, 2021.

The agency is changing its standard timeframe for delivering first-class letters, flat envelopes and periodicals. The benchmark will go from a one-to-three-day window to a one-to-five-day window for mail sent within the contiguous United States.

For first-class mail coming from the contiguous U.S. and going to Alaska, Hawaii, Puerto Rico or other U.S. territories (or vice versa), the standard will be four to five days.

Most first-class mail – an estimated 70% – will still arrive in under three days, according to a notice by the USPS in the federal register. In general, the delays will affect pieces of mail that have to go farther, from coast to coast or far reaches of the U.S.

The slower timeframe allows USPS to shift more of its delivery service away from air transportation and deliver more mail via ground transportation. The agency says air mail is more susceptible to unexpected weather delays and costs more, so the new system will be cheaper and more reliable.

WHNT