Over the past third of a century the Incorporated Research Institutions for Seismology (IRIS) has facilitated observational seismology in many ways. At the beginning of IRIS in 1984, and with the support of the National Science Foundation and in partnership with the US Geological Survey, IRIS embarked on deploying the Global Seismographic Network (GSN). Key characteristics of the GSN are its use of high-performance digitizers, very broad band seismometers, strong motion accelerometers, and high frequency sensors to provide multi-decadal observations across a wide frequency band and dynamic range. The IRIS Portable Array Seismic Studies of the Continental Lithosphere (PASSCAL) program has also operated since 1984. PASSCAL’s extensive inventory of seismic equipment has been used by scientists to make observations on every part of the globe. The number and breadth of observations made with this equipment has fueled thousands of research papers and contributed to the education of hundreds, if not thousands, of students. More recently, the IRIS-operated EarthScope Transportable Array (TA) provided a breakthrough in the systematic collection of data using an array of unprecedented size. The success of the TA has ushered in a new era of “Large N” seismology, focused on dense spatial coverage of sensors to reduce aliasing and provide more complete recording of the full wavefield. The TA highlighted the power of survey mode data collection, where systematic, spatially-dense, and high-quality data fuel data-driven discovery, as opposed to deployments made to test a specific hypothesis. Key future directions in observational seismology include an increasing emphasis on wavefield measurements. Deploying instruments in large numbers requires reductions in the size, weight, and power of units, as well as a focus on dirt-to-desktop data management strategies that merge data and metadata while minimizing human intervention with the data flow from the sensor in the dirt to the scientist’s desktop. Other critical frontiers include pervasive seafloor observations to enable studies of key structures like subduction zones, more accessible satellite telemetry to enable ubiquitous sensing of the environment, and new sensing technologies such as MEMS and Distributed Acoustic Sensing.