If California had half the number of Coronavirus cases in New York, then the number of cases was 2000/2 = <<2000/2=1000>>1000 cases.
California had 400 more cases than the state of Texas, thus Texas had 1000-400 = <<1000-400=600>>600 cases.
The total number of Coronavirus cases in all of the three states is 600+1000+2000 = <<600+1000+2000=3600>>3600 cases.
#### 3600