Los Angeles County which has a population of 9,818,605. The county itself is more populous than 42 states.
The most populated county in the US is Los Angeles County in California with a total population of 9,878,554.
Cumberland County in Maine has the highest population compared to other counties in the state. Its county seat is Portland, which is the largest city in Maine.
King County
According to census.gov, the 2007 population estimate for Maricopa County, Arizona, is 3,880,181.
According to census.gov, Hennepin County, Minnesota, has the most population at 1,136,599 people.
The smallest county by population in Wyoming is Niobrara County with 2,484 people (2010 US Census).
There are 53 counties in North Dakota. Cass County is the most populous county in North Dakota with a population of 149,778 per the 2010 U.S. Census.
In area, Sweetwater County is the largest county in Wyoming with a total area of 10,491 square miles (27,172 km²), of which 10,425 square miles (27,001 km²) is land and 66 square miles (171 km²) (0.63%) is water. Sweetwater county is also the 8th largest county in the US. By population, the largest county in Wyoming is Laramie County with a population of 91,738 according to the 2010 US Census.
Cass County, with a population of 149,778 in the 2010 US Census, is the most populated county in North Dakota. The largest city in North Dakota, Fargo, and the fifth largest city, West Fargo, are both located in Cass County.Cass County, North Dakota. With a population of 123,138.
According to census.gov, Harris County, Texas, has the most population at 3,935,855 people in 2007.
According to census.gov, Pulaski County, Arkansas, has the most population at 373,911 people in 2007.
According to census.gov, Multnomah County, Oregon, has the most population at 701,986 people in 2007.