Wikipedia:Wikipedia is timeless

Wikipedia is timeless. In other words, the age of a subject should not affect its inclusion, either as a separate article or part of another. As long as sufficient reliable sources are present, the same topic should, in theory, have comparable coverage whether it existed one year ago or 200 years ago.

For example, suppose consensus is formed that all operating railroad companies should be covered. Then Wikipedia should also have information about railroad companies that have operated in the past, and the fact that they no longer operate is not a reason to delete. Similarly, if there is a list of railroad companies in a place, former companies should be either included in that list or in a separate list.

What this does not mean

 * Articles on recent topics should not be stunted or deleted just because articles on older topics have less information or do not exist.
 * We should not necessarily cover an older subject just because a similar newer subject has coverage (see Arguments to avoid in deletion discussions). But the fact that the older topic no longer exists is not in itself a reason to delete.
 * If examples are given, rather than a full list, it may be best to restrict those to recent cases, so that it is more likely that the reader will be familiar with them.