text: Regional reconstructions are generally more worthwhile than reconstructions from a single site because, if there is shared variance, the regional result is likely to be more robust and be more representative and that makes it more valuable for continental and hemispheric comparisons. The key issues are whether all the trees (or some subset of them) share a common signal (are they mostly temperature sensitive? are some localities anomalous? etc.). It isnt as simple as just averaging all the trees in a grid box or two. The history of such efforts follows a mostly standard path local chronologies are put together, different standardisation techniques are applied, more data is collected, wider collations are put together, and then regional reconstructions start to appear.