The United States Precision Lightning Network (USPLN) is a large-scale lightning detection network designed to detect cloud-to-ground lightning strokes over the continental United States. The USPLN was first built and deployed operationally in 2004 as a joint initiative between TOA Systems, Inc. and Weather Decision Technologies (WDT). In 2007, WSI Corp. acquired WDT's interest in the USPLN and continues to operate the USPLN jointly with TOA Systems.

The USPLN uses time-of-arrival sensors connected via the internet to central processors as the basis of its detection system. The sensors are responsible for detecting lightning signal waveforms in the VLF through MF spectrum and reporting the time of arrival and other characteristics of the waveform to the central processor. The central processors use time-difference of arrival techniques to ascertain location, time and other characteristics of the stroke. The USPLN is a stroke detection network (as opposed to a flash network) with each stroke in a flash detected, solved and reported independently. The sensors have a 300 to 500 microsecond dead time between strokes allowing for effective stroke detections. Network simulation experiments have shown that the USPLN is capable of 95% or better ground stroke detection efficiencies, with RMS location accuracies less than 250 m. Numerous anecdotal verification studies have indicated the network has achieved this efficacy. Since the USPLN uses the internet for all communications, end users typically can receive lightning strike data within 15 s of occurrence, and often less.

The original USPLN deployed over 100 sensors roughly uniformly across the CONUS. With recent and ongoing deployment of additional sensors, the coverage of the USPLN has expanded significantly into Alaska, Canada, Central America, the Caribbean and South America. By the end of 2008, the network will consist of about 150 sensors contributing to a broad detection capability across the Americas. With this additional coverage, the USPLN is being rebranded as the North America Precision Lightning Detection Network or NAPLN. In addition, WSI and TOA are expanding lightning sensor coverage overseas and throughout the oceans with the goal of providing useful global lightning detection capabilities by the end of 2008.

Data from the USPLN are available in multiple forms, formats and communication protocols both through value-added resellers as well as direct from the USPLN. Data is also available to the academic research community free-of-charge for use in research and development projects through the UNIDATA LDM Program.