Postal service

These used to be available in nearly every bookstore, every news stand, every five-and-dime and every corner drugstore; hotel and motel operators routinely distributed free, blank postcards which contained an advertisement for their inns. They are becoming a bit harder to find now that e-mail is cheap and postal mail is expensive. An independent bookstore may still be worth a try; souvenir shops at individual attractions and tourist information bureaux may either have blank cards for sale or know who does have a few left.
In some countries, the post office may have blank postcards, but these tend to be generic; the images are of the country as a whole and not the specific town you're visiting. A few countries (such as the United States, for USPS First Class Mail) may allow postcards to be mailed at a slightly cheaper rate than other first-class correspondence. In some cases lower rates apply for postcards in domestic mail only and international postcards are sent at the same (higher) rates as international letters. The cards need to be within a specific size range (at least 3.5 x 5" and typically 4x6", printed on stock thick enough to not jam during automated sorting) to qualify. Turning one of your own 4x6" travel photographs into a postcard is possible, but the printed image will either need to be glued to cardstock or printed on heavier-than-standard cardstock so that it will go through the sorting machine undamaged.

Availability of postage stamps varies between countries. One cannot usually count on finding them at every grocery store, so stocking up on stamps on arrival in a new country might be a good idea. In the worst case, post offices are the only place to buy stamps — and they're often closed on weekends. Some countries also have stamp vending machines. While they have the benefit of (usually) being available year round at any hour, the machine produced stamps are almost always of a rather bland, standardized design. Often stamps are available in shops that sell postcards, but they might not want to sell you stamps if you don't buy postcards there as well. A few countries operate franchised "postal substation" or retail post office counters at the back of chemist's shops or other retail businesses; hours of operation vary but are usually better than those at the main station.
To be certain that postage stamps are available for mail on a trip, and they are of a certain design, visit the online shop of the postal service in question when planning for the trip.
Many stamps are beautiful; if visiting a small or remote country, they make nice souvenirs at a low cost. Small territories like Montserrat, if they issue their own local postage, often operate a philatelic bureau just to feed the appetite of foreign collectors for rare and colourful stamps. Most countries issue series or sets of stamps during limited time periods to commemorate individual events or famous people. These are usually available from any post office.

A few post offices display unusual or seasonally-themed names such as "North Pole", "Bethlehem" or "Santa Claus" which are a popular novelty when sending greeting cards.
There are various schemes which generate "North Pole" or Christmas-themed mail. Not all involve travel:

• An obvious possibility is to travel somewhere like "North Pole" and send holiday greetings directly from there. In some cases, there will be a Santa-themed amusement park (one in North Pole NY pre-dates the Disney parks by six years, with a postal substation in the theme park); in others, the holiday-themed town name is little more than coincidence.
• A few souvenir vendors in North Pole (Alaska) have been known to sell a personalised "Santa letter", sent by regular mail with the seasonal North Pole 99705 postmark. Streets in this population 2200 town often have names like "Santa Claus Lane".
• Less cynically, in some countries volunteers ensure a postal reply for Santa-related mail. For instance, a letter to "Santa Claus, North Pole H0H 0H0 Canada" will be answered, no travel required.
• Can't make it to the North Pole or even Bethlehem (Pennsylvania)? Post offices in many of these places offer a Christmas or holiday re-mailing service, where one can bundle a stack of stamped, addressed greeting cards into a package addressed to the local postmaster, who sends them onward.

A similar holiday remailing scheme, operated since 1946 by volunteers, stamps a Loveland (Colorado) postmark and a verse on Valentine's Day mail "From The Sweetheart City." Romeo Michigan and Juliette Georgia have issued matching seasonal picture postmarks since 1994 as an implicit literary reference. Other options include Valentine Nebraska, Romance Arkansas and Loving New Mexico.
If you travel longer distances by boat it is often possible to post mail on board, using postage stamps of the country where the ship has home port, or postage stamps of the country where you boarded the ship. On passenger ships it might even be possible to buy postage stamps, and perhaps there is a mail box. Mail is handed in at the ship reception desk or to the ship clerk. The postcard or letter will receive an auxillary stamp with either the text paquebot (French for ship mail) or the equivalent in another language. Mail is then posted in first coming port and gets a local postmark. This kind of mail is collected by specialised philatelists.

Due to its historic role as a primary means of intercity communication, the postal service has a rich history. Among the points where it has left its imprint are:

• Post roads, such as the 1800 mile Pony Express National Historic Trail. In the horse and stagecoach eras before rail travel, the first usable all-season road into a community was often the "post road" used to bring the mail into town.
• Railway Post Office (RPO) cars, in which mail was sorted en route as a train moved between towns and cities.
• Royal mail ships and vessels, a designation proudly displayed by ocean liners in the steam era. A fast passenger ship in the RMS Titanic era could earn valued boasting rights for reliably getting mail to its destination on time.
• Historic transport of valuables and currency by registered mail. This led to events such as the Great Train Robbery (United Kingdom, 1963) in which substantial sums of money were stolen by intercepting a Royal Mail train. Robbery of valuables travelling as registered mail was also a common theme in the Old West.

There are entire museums devoted to postal history or philately:

• An Post Museum in a corner of Dublin's GPO in Ireland
• The British Postal Museum & Archive in London, England
• National Postal Museum, Smithsonian Institute, Washington, DC, USA
• The Post Museum, above the Central Post Office at Al-Ataba Square, Cairo, Egypt
• Cuban Postal Museum, ground floor of the Ministry of Informatics and Communication, near Revolution Square Havana, Cuba.
• First Toronto Post Office, 260 Adelaide St E, Toronto, Upper Canada. A British Royal Mail building from 1834, today a museum with a few postal and local history exhibits. Visitors may send folded-sheet letters using old-fashioned quill pens and sealing wax.
• Bath Postal Museum in Bath, UK
• Postal History Foundation, Tucson, Arizona, USA
• A postal museum is included in Charleston's Museum Mile in South Carolina, USA
• Delphos Museum of Postal History (open to groups by appointment) in Delphos, Ohio, USA
• Spellman Museum of Stamps & Postal History in Weston (Massachusetts), USA

(This list is not comprehensive; see also postal museum and list of philatelic museums on Wikipedia.)
In many cities, a current or former main post office building is an architectural landmark or appears on a national historic register. One example would be the main New York City post office (8th Ave at 34th Street, postcode 10001) with the famous inscription "Neither snow nor rain nor heat nor gloom of night stays these couriers from the swift completion of their appointed rounds." As a seasonal custom, holiday mail sent as in the closing scenes of "Miracle on 34th Street" (1947 film) is answered with the aid of volunteers.
Because postal mail readily migrated to each new form of transportation, from pony express to airmail, in search of faster time to destination, its history extensively overlaps that preserved in other museums and archives such as heritage railway museums, marine museums and transportation museums. In some remote communities, the only scheduled passenger service is still aboard the bush plane which provides or used to provide scheduled mail delivery; in the 1980s, a post bus was a bright-red Royal Mail passenger van which carried people and mail to remote Scottish villages unable to sustain a stand-alone passenger coach service. In more modern times even high speed rail was used to deliver mail with the French TGV la Poste. While they are no longer in use, they are not found in a museum (yet).

A few options exist:

• The hotel (or, for those cruising on small craft, the marina or yacht club) might be willing to accept mail – but is not required to do so. Unlikely to be an option unless you're in one place for a long time. They might delay the delivery.
• Mail may be held at a main post office as poste restante or general delivery for pickup at the counter; costs vary. In some countries this is free or almost-free, in others it's no cheaper than renting a post office box.
• When staying at an address for a longer period of time, an address where you are not permanently registered, it is possible to use care of in the address. Mail should then be directed to "your name" c/o or ℅ "another person's name", either at a physical address or at a post office box. It is important that you have consulted the other person on this procedure and the other person has agreed to this. You might end up not receiving your mail if the person has not agreed.
• Mail and parcels may be sent to a commercial mail receiving agency or private mailbox such as PakMail or UPS Store/Mail Boxes Etc. Many of these will blindly sign for anything that arrives, then either hold it for pickup or forward it at your expense. In the US, kinek.com maintains a list of local merchants who will sign for an individual parcel and hold it for pickup. Cost is typically more than a standard post office box ($20-25/month or $5/parcel is typical), but these are useful when dealing with mail-order merchants who insist on sending purchases by private couriers instead of as postal express mail.
• A very small number of commercial mail receiving agencies offer a mail scanning service, in which incoming paper mail is scanned to e-mail for delivery on-line. Uptake of services like "Earth Class Mail" has been slow, due both to cost and the inherent lack of privacy.

For short trips, it may make more sense to have your home post office hold your mail (or a friend check it) until you return instead of forwarding it to reach you during your travels.
If you are staying longer than a couple of weeks, it might make sense to get an address you may have post sent to and give it to those you wish (or have to) receive letters from. Check whether you can get post that for one reason or another arrives late, after you have left.

A commercial mail receiving agent may be of assistance if you're sending baggage ahead in mail or courier parcels to avoid carrying it on airline flights. This approach has advantages and disadvantages; it avoids punitive extra charges which airlines now demand for excess checked baggage, but the parcels don't necessarily arrive at the same time you do. Business travellers sometimes prefer to send samples, tools and spare parts ahead instead of carrying them as this encounters fewer customs issues - the company has access to customs brokers to handle the paperwork and the voyager is spared the "you're here to work illegally?" responses that these items attract when carried across the border.
In case you purchase far more souvenirs than expected, and it is impossible to place all of this in your luggage, consider sending lightweight and non-fragile items by parcel to your home address. This can be less expensive than booking extra luggage at the airport, and might save time that should have been spent waiting at the airport customs in your home country, if applicable. You might just send your dirty laundry by parcel, since clothes are lightweight and unsensitive to rough treatment. Make sure the parcel is well-packaged to avoid damages to content and packaging. You may even - if time and local postal regulations allow - send items by post that airport security will not allow you to bring aboard an airplane.