Cut nails (so called because they were cut from a larger sheet of iron or steel) largely replaced handmade nails during the early to mid 19th century. This was huge- widespread availability of a previously rare building material meant the decline of timber-framing (where large timber members are fitted and joined to one another) and the rise of balloon and platform framing, where framing members are attached to one another with nails.
Though cut nails ushered in an era where the metal fastener went from being a scarce luxury to a mass-produced commodity, their relevance was short-lived: by the late 19th century, wire nails (picture a nail…you’re picturing a wire nail) soon replaced cut nails as the fastener of choice. By 1892, more wire nails were being produced than cut nails and by 1913, 90% of the nails being produced were wire nails (thanks, Wikipedia).
Our houses were built around 1907, and all of the framing in our houses uses cut nails, so it’s likely that the nails we’re pulling from joists and studs were some of the last cut nails used in Baltimore before wire nails replaced them.