From the above Fig. 2 it is clear that NYT is now, and for some time has been, reporting noticeably more cases nationally compared to either COVID Tracker or USAFacts. The absolute difference in reported cases between NYT and COVID Tracker, as well as that between NYT and USAFacts, has also been increasing for most of the past two months (i.e. all of April and May) Another pattern that has been ongoing for some time now is that NYT is reporting more cases than JHU, and the difference between these two has also generally been increasing over the past two months. Nevertheless, it is noteworthy that JHU is reporting more cases than either COVID Tracker or JHU, and that, again, both the gap between JHU and COVID Tracker and the gap between USAFacts have been steadily increasing for most of the last two months. Finally, COVID Tracker and USAFacts have been reporting the most similar numbers of nationwide cases of any two trackers included here, as is evident from the differences line for COVID Tracker-USAFacts in Fig. 2 having mostly fluctuated closer to the x-axis than any of the other five.

During all of March and the first few days of April, COVID Tracker reported more cases nationwide than did JHU. (Note that all subsequent figures refer to national data unless indicated otherwise.) However, on April 5, this changed and JHU's case count surpassed that of COVID Tracker. This has remained the case ever since, so that as of May 31, JHU was reporting 6,602 more cases nationally than COVID Tracker. 

The Pearson correlation between the number of cases reported by COVID Tracker and JHU was 0.9999971.

On March 3, 2020, COVID Tracker was reporting just 1 more case than NYT. COVID Tracker's lead over NYT then grew until it reached its peak of 4,643 cases on March 23, at which point it started shrinking. By April 2, this lead had been completely eliminated and NYT was now on top, reporting 467 more cases than COVID Tracker. Since then, the NYT's lead over COVID Tracker has grown to 15,194 cases (as of May 31).

The Pearson correlation between the number of cases reported by COVID Tracker and NYT was 0.9999970.

From January 24 to February 29 inclusive, USAFacts was reporting more cases nationally than COVID Tracker. But this changed on March 1, when COVID Tracker reported a total of 4 more cases than USAFacts. This was the first time that COVID Tracker reported more cases than USAFacts, a pattern which continued until April 3, when the number of USAFacts cases surpassed the number reported by COVID Tracker by 1,017 (by contrast, the day before, April 2, COVID Tracker was reporting 2,291 more cases than USAFacts). Since then, these two trackers have exchanged positions relative to one another ten times (as of May 31).

The Pearson correlation between the number of cases reported by COVID Tracker and USAFacts was 0.9999970.

From April 5 to May 31 inclusive, JHU has reported more cases than COVID Tracker. JHU reported 1,690 more cases on April 5 and 4,542 more cases than COVID Tracker on May 31.