In the controlled and restrictive environment of prisons, access to money is limited. Physical cash is not permitted inside most facilities, and transactions must follow strict institutional guidelines. Yet, an informal economy still exists—one in which U.S. postage stamps serve as a preferred medium of exchange. This article explores why stamps have become currency in prison systems across the United States.

The Basics of Prison Economies

Prisoners, despite their incarceration, still engage in trade. They seek out services, bartering for everything from commissary goods and hygiene products to personal favors like haircuts, laundry, or even protection. Since inmates cannot legally possess traditional forms of money, they’ve adapted by relying on items that are both valuable and permitted by facility rules.

Among the various commodities used—such as ramen noodles, instant coffee, and mackerel pouches—postage stamps are one of the most standardized and widely accepted forms of currency.

Why Stamps?

Several factors contribute to the popularity of stamps as currency in prison:

1. Consistent and Recognized Value
Each stamp holds a clearly defined, nationwide value set by the U.S. Postal Service. As of 2025, a Forever Stamp can be used to mail a standard letter regardless of future rate changes, making it stable and predictable.

2. Portability and Discretion
Stamps are compact, lightweight, and easy to conceal, which makes them practical for low-profile trades. Inmates can carry a few stamps without drawing unwanted attention from staff.

3. Institutional Approval
Unlike other traded goods that may be contraband or restricted, stamps are generally permitted in most prisons. They can be purchased through commissary and mailed into facilities in limited quantities, giving them a sanctioned legitimacy.

4. Wide Utility
Stamps are one of the few prison commodities that have legitimate use both inside and outside of trade. Inmates use them to send letters to loved ones, file paperwork, and communicate with attorneys. Their practical utility reinforces their economic value.

Trading Stamps in the Informal Market

In prison, barter is the cornerstone of commerce. A haircut might cost two stamps. A homemade snack might be worth three. Some inmates keep track of debts using stamp-equivalents, even if physical stamps aren’t always exchanged on the spot.

While rules prohibit trading in many facilities, enforcement varies, and barter continues to flourish in ways that mimic free-market systems. Stamps function like paper money—easy to count, split, and trade.

The Role of Commissary and Postal Limits

Access to stamps is tightly controlled. Inmates can usually buy them through commissary accounts or receive them from approved outside sources. However, limits on the number of stamps an inmate may possess at one time are common.

These limitations can actually enhance the stamp’s power as currency. Because supply is somewhat restricted, demand remains high, sustaining their trade value.

Risks and Consequences

Although the use of stamps as currency is widespread, it is not officially sanctioned. Correctional officers may confiscate stamps if they suspect misuse, and inmates caught operating sophisticated trade networks can face disciplinary actions.

There are also risks of exploitation. Stronger inmates may pressure others to give up stamps or engage in unequal exchanges. As with any unregulated economy, the lack of oversight can result in abuse and inequity.

Evolution Over Time

The rise of digital communication and prison email systems has challenged the necessity of physical stamps, but their presence in the informal economy remains strong. Even as technology enters correctional systems, stamps continue to symbolize stability and value.

In the absence of money, incarcerated individuals have created a resourceful workaround to sustain social and economic interactions. Stamps, with their recognized value, practical use, and institutional accessibility, have become a preferred medium of exchange.

The question of “why are stamps currency in prison” reflects broader insights into adaptability, social structure, and survival strategies under constraint. Stamps are not just tools for mailing letters—they are a window into the resourcefulness of life behind bars.