Postage hike: The largest stamp increase in U.S.P.S. history has gone into effect

The largest stamp price increase in U.S. Postal Service history has gone into effect.

The cost of a Forever stamp has gone up a nickel to 55 cents.

That's the largest increase in stamp costs since 1991, according to USA Today.

But while the first-class stamps will be more expensive, the USPS says it will lower the price per additional ounce for letters, decreasing from 21 cents to 15 cents, according to the price breakdown from the USPS.

It will also get more expensive to ship items. Priority Mail flat rate prices will increase. A medium flat rate box that shipped for $13.65 will now cost $14.35.