Top five counties of the United States of America are Los Angeles, Cook, Harris, Maricopa and San Diego.
Step-by-step explanation:
The top most county of the United States of America which is the most populous county is Los Angeles which is in California. The population of that county is 10,105,518. The second most populated county is Cook which is in Illinois and the population of this is 5,180,493. The third one is Harris which is located in Texas and the population of this is 4,698,619.
The fourth county is Maricopa which is located in the state of Arizona and the population is 4,410,824. The fifth most populous county of the United States of America is San Diego which is in California and the population of this is 3,343,364.