Even in a digital society, hardcopy documents must be sent. Postage rates depend on the size and weight of the envelope or package and the delivery time. The sooner a correspondence must be delivered, the more it will cost. Sending a letter overnight through the United States Postal Service's Express Mail begins at $13.25 with prices increasing as weight and distance of delivery rises. Priority Mail prices begin at $4.95 with a delivery time of between one to three days.

First class mail is categorized as cards, letters, large envelopes, or packages. Cards are rectangular cardstock no larger than 4 ¼" × 6" × 0.016" thick mailed without an envelope for 28 cents. Letters are contained in rectangular envelopes measuring no more than 6 ⅛" × 11 ½" × ¼" thick with a maximum weight of 3.5 ounces. Letters weighing up to:

• one ounce cost 44 cents
• two ounce cost 61 cents
• 3 ounces cost 78 cents
• 3.5 ounces cost 95 cents

Large envelopes are flat and rectangular with a maximum size of 12" × 15" × ¾" thick and a maximum weight of 13 ounces. Prices range from 88 cents for up to one ounce to $2.92 for 13 ounces. The sum of the length, width and thickness of packages must be less than 108 inches. Packages cost from $1.22 for up to one ounce to $3.26 for 13 ounces.

The United States Post Office was established by the Second Continental Congress on July 26, 1775 under Benjamin Franklin. In 1792, the postal service became the Post Office Department and remained part of the United States Cabinet until 1971 when the United States Postal Service became an independent establishment of the executive branch of the United States.

Postal rates have always been dependent on the size of the letter and the distance of delivery. On June 1, 1792, a single letter of one sheet of paper cost 6 cents for delivery within 30 miles. The rate was raised on May 1, 1799 to 8 cents for a single letter for delivery within 40 miles. Rates for all letters and distances were increased by 50% on February 1, 1815 to pay for the War of 1812. The rate increase was repealed a year later on April 1, 1816. Postage rates were lowered again on May 1, 1816 to 6 cents for a single letter for delivery within 30 miles. On July 1, 1845, rates became dependent on the weight of a letter and rather than the number of sheets in a letter. A letter weighing up to ½ an ounce for delivery within 500 miles cost 5 cents. Six years later, on July 1, 1851, a letter weighing up to ½ an ounce for delivery within 3,000 miles cost 3 cents prepaid, 5 cents not prepaid. Postage may be prepaid by the sender or collected from the recipient, not prepaid. Letters were required to be prepaid beginning April 1, 1855. From 1863 until present day, postage rates have increased 26 times.

Stamps were authorized by Congress on March 3, 1847 when sending a letter weighing up to 1 ounce for delivery within 300 miles cost 5 cents. An image of Benjamin Franklin graced the 5 cent stamp and remained in circulation until July 1, 1851. The Forever stamp was issued for the first time on April 12, 2007.