WASHINGTON -- How many stamps would you buy if you knew the price would never go up?

Even as the Postal Service's governing board voted Wednesday to seek a 3-cent increase in the price of a stamp to 42 cents, it is proposing a "forever" stamp that could always be used to mail a letter no matter how much postal rates go up.

The earliest a rate increase would go into effect is next May, if approved by the Postal Rate Commission.

The forever stamp would help soften the blow of a rate increase by allowing customers to stock up.

It would sell for the first class rate and, once purchased, the special stamp would remain valid for whatever the first-class rate is when it is used, regardless of future increases.

Wednesday's request for an increase in the stamp price goes to the independent Postal Rate Commission, which has 10 months to act.

The cost of a first-class stamp went from 37 cents to 39 cents in January. Before that, the price had been unchanged since 2002.

The proposed increase would boost the price of mailing a letter to 42 cents.

Rates will change for other types of mail also.

For example, it currently costs 63 cents to mail a two-ounce first-class item whether it's a letter, large flat envelope or package. But the post office makes more than 30 cents on the letter, 10 cents on the flat and loses money on the package.

That means the agency will be looking at shape as well as weight in setting new rates, officials have said, particularly in the face of a decline in first-class mail as more people pay bills and send messages via the Internet.