Nitrous oxide (N<sub>2</sub>O) is a potent greenhouse gas and ozone-depleting substance. Approximately 42 % of anthropogenic N<sub>2</sub>O emissions are thought to be emitted from urban areas. We tested three N<sub>2</sub>O analyzers for their suitability to measure N<sub>2</sub>O in urban areas from tower and mobile platforms. All three analyzers (Aerodyne SuperDUAL, Aeris MIRA Ultra, and LI-COR LI-7820) have sufficient precision for urban measurements but require different amounts of calibration and attention for best results. Using these analyzers, we observed tower-level enhancements at least 3 times larger than predicted from the best available inventory for the NYC region. Co-measurement of carbon monoxide (available on all but the LI-7820) were used to identify combustion-related enhancements of N<sub>2</sub>O. Mobile driving confirmed that traffic related emissions for NYC are captured by the inventory and that wastewater treatment is the most likely source for the missing N<sub>2</sub>O emissions.