General Delivery is the free way to get mail while you are traveling, and USPS puts four limits on it in writing: it is meant for transients, it works at one facility, the postmaster can refuse you, and each piece is held no more than 30 days. All four sit in the Domestic Mail Manual at section 508.6, which we read on 2026-08-14.
What the manual says
Who it is for. “General delivery is intended primarily as a temporary means of delivery: For transients and customers not permanently located. For customers who want Post Office box service when boxes are unavailable” (DMM 508.6.1). If you are moving through, you are the intended user. If you have parked in one town for a season, you are closer to the edge of the definition, and the manual gives the postmaster room to act on that.
One location. “General delivery is normally available at only one facility under the administration of a Post Office with multiple facilities,” and “A customer may use only one such location” (DMM 508.6.2). In a city with several post offices, exactly one takes General Delivery, and it will not necessarily be the one nearest to where you are parked.
The postmaster can say no. The same section lets a postmaster refuse or restrict service to a customer “who is unable to present suitable identification” or one “whose mail volume or service level (e.g., mail accumulation) cannot reasonably be accommodated.”
Thirty days per piece. “Each general delivery mailpiece is held for no more than 30 days, although a shorter time period may be requested by the sender” (DMM 508.6.4). Per piece, from arrival, and the sender can shorten it. A box that lands the week your plans change is a box that goes back.
The step most people skip
The manual tells you to make one phone call: “Prior to mailing, customers should contact the destination Post Office to determine the authorized facility or facilities and their applicable ZIP Code(s)” (DMM 508.6.3). That call prevents both common failures, mail sent to a branch that does not hold it and mail sent under the wrong ZIP.
One fallback the manual rules out
If you were thinking of Premium Forwarding Service Residential as the backup plan, read DMM 508.7.2.5 first. It is not available to customers whose primary address is “a central point to which the USPS provides delivery in bulk to a third party, such as a commercial mail receiving agency (CMRA), RV park, trailer park,” among other categories. A mail-forwarding service address is exactly that kind of address, so the service most full-timers already pay for is the one that disqualifies them here.
One more honest limit: the DMM governs USPS mail. It says nothing about private carriers, and we did not verify what UPS or FedEx do with a General Delivery address, so do not assume a package shipped that way arrives at all.
How to actually use it
Pick a town on your route with a post office you will pass anyway. Call it, get the authorized facility and the General Delivery ZIP, and give the sender a window that lands inside 30 days. Address it to your name, then General Delivery, then the city, state and that ZIP. Bring ID to the counter.
If you are wintering on public land, plan the mail stop the way you plan water: around a town you were already going to visit. Our Arizona free camping page and the RV living hub cover the rest of that logistics chain.