Production of 1848 Dimes took place only at Philadelphia and was limited to 451,500 circulation strikes. Even so, this was a significant increase over the previous year's mintage, thus this date can be found with relative ease for prices not too much over those of a common type coin. Mint State examples are scarce but not rare, and several nice MS64's exist. The best examples are MS65's, but only a few exist at that level.
Gerry Fortin identified two different die pairs for the circulation strikes and one die pair for the Proofs. All seem to have used the same date logotype, thus references to a Medium Date are confusing -- they are all the same size.