The economic sustainability of production from shale gas and tight oil resources is coming into sharper focus as oil and gas prices remain low, relative to the prices that spurred extensive drilling programs in recent years. Large variability in the initial production rates of wells even within similar areas of drilling is a point of particular concern. In addition to the economic risk this creates for oil and gas companies, the high degree of well-to-well variability makes it a challenge to reliably assess the scale of recoverable resources, the environmental impacts of development, and ultimately the future role of shale gas and tight oil. Here we show that there is a consistent scale-invariant pattern to initial well production rates in major U.S. shale plays, which can accurately be described by a lognormal distribution. This characterization is valid for spatially contiguous well ensembles in both core and non-core areas of fields, for ensembles of different vintages (year of initial production), and for well portfolios of individual operating companies. Recognition of this distribution is an essential step for accurately characterizing the short-term economics, long-term recoverable resource, and environmental impacts of these resources development.