When comparing patent litigation rates or “rarity” across decades, one must take into account the proportion to the actual scale of commercial activities that give rise to patent disputes. Such normalizing scales are preferably national metrics of commercial activity such as (a) the number of patents issued in the year, (b) the total number of patents in force over which disputes may arise, (c) the total number of Federal civil suits, or (d) the economic scale of the Gross National Product (GDP) in real dollars. This paper marshals for the first time information on all patent litigation in Federal district courts spanning almost a century. The patent lawsuit filing information is newly obtained from the Judicial Conference Annual Reports going back to 1937 and further collected from the weekly Official Gazette of the Patent Office going back to 1923. In addition, an estimate for the number of US patents in force in each of the years covered is derived. Using non-parametric statistical tests, it is shown that, with the exception of the AIA-caused litigation anomaly of 2011-2013 explained in the paper, for all four normalizing metrics, patent litigation intensities during this century had not exceeded those experienced during the 20th century. High patent litigation intensities in the 1920s-1930s and the 1960s have been comparable to, if not higher than, those in the 2000s. These litigation activities are thought to be consistent with major shifts in technological developments such as the development of radio and electronics and chemical advances in the 1920s-1930s, the development of semiconductor transistor electronics in the 1960s and the wireless communications and internet-based technologies at the turn of the 20th century.