Throughout the U.S., there are clearinghouses that store information on the known archaeological sites within each given state. The name and organization of these clearinghouses varies from state to state, but in California they are known collectively as the California Historic Resources Information System (CHRIS) and consist of regional offices that house the site records for the surrounding area.
Archaeological site location information is considered sensitive, as there is a long tradition of people looting sites. As a result, in order to get information from the clearinghouses, you typically have to show that you are either a legitimate and responsible archaeologist or the owner of the land on which a site is located, and you have to sign a confidentiality agreement. However, this creates a tension, as the rationale behind most of the laws protecting sites is that the sites are of importance to the people of the United States. So, we preserve them based on the premise that they are important to the people from whom we hide their locations.
This also makes it a bit of a pain to gather information on known sites within a given area. So, if you happen to be an archaeologist with a project in, say, northern San Luis Obispo County, you need to go through the process of having a record search done at the CHRIS information center in Santa Barbara, complete with confidentiality agreements, making appointments (or waiting for the info center personnel to have a chance to do the search for you), and a bit of a hassle.
To this end, many of the information centers around the country have been working to create digital archives of their holdings in order to free up space and make searches easier. This has resulted in a discussion within the archaeological community regarding whether or not to make this information available online.
The upside to online searches is that they would allow an archaeologist to get results within days or even hours, rather than the weeks or months that it currently takes. It would also reduce the overall costs of running the info centers (less workspace needed), as well as reduce the inconvenience to our clients when we are waiting for search results.
The downside is that site location information would be readily available to those who would like nothing better than to loot sites, destroying them in an effort to get collectable or sellable artifacts out of them. Certainly, websites can be password-protected, but these passwords only provide so much safety, and are routinely bypassed by those with sufficient knowledge - just ask anyone who runs a membership-driven website.
A few years back, I attended a session at the Society for American Archaeology annual conference on the issue of improving access and performance of systems such as CHRIS. One of the attendees, a representative of the the state historic preservation officer for one of the southern states (I don't recall which one) stated that we should simply put everything online, and that we are worrying too much about what "one guy with a shovel" can do.
But the problem is that "one guy with a shovel" can do alot of damage - most of the historic archaeological sites that I saw while working around Taft last year were heavily looted and disturbed, and I have been present on more than a few prehistoric sites where looters have nearly destroyed the entire site. It gets worse when you consider that, very often, we aren't even dealing with "one guy with a shovel", but rather with groups of people with shovels, backhoes, and (in at least one case that I know of) heavier equipment such as bulldozers. It bothers me that we keep site location information secret, but it bothers me even more that once a site's location becomes widely known said site becomes a magnet for looters who will use whatever equipment they can get their hands on to pull things out for either their personal collections or for sale.
It's a thorny issue - how do we maintain public communication while hiding some of the most basic information about a site - and one to which I don't have a solution. Until one is found, though, I don't see any alternative but to keep location information confidential.