County

2000
Population

Square
Miles

County Seat

Founded

Bernalillo County

556,678

1,166

Albuquerque  

1852 

Catron County

3,543

6,928

Reserve  

1921 

Chaves County

61,382

6,071

Roswell  

1889 

Cibola County

25,595

4,540

Grants  

1981 

Colfax County

14,189

3,757

Raton  

1869 

Curry County

45,044

1,406

Clovis  

1909 

De Baca County

2,240

2,325

Fort Sumner  

1917 

Dona Ana County

174,682

3,807

Las Cruces  

1852 

Eddy County

51,658

4,182

Carlsbad  

1887 

Grant County

31,002

3,966

Silver City  

1868 

Guadalupe County

4,680

3,031

Santa Rosa 

1891 

Harding County

810

2,126

Mosquero  

1921 

Hidalgo County

5,932

3,446

Lordsburg  

1920 

Lea County

55,511

4,393

Lovington  

1917 

Lincoln County

19,411

4,831

Carrizozo  

1869 

Los Alamos County

18,343

109

Los Alamos  

1949 

Luna County

25,016

2,965

Deming  

1901 

McKinley County

74,798

5,449

Gallup  

1899 

Mora County

5,180

1,931

Mora  

1859 

Otero County

62,298

6,627

Alamogordo  

1899 

Quay County

10,155

2,875

Tucumcari  

1903 

Rio Arriba County

41,190

5,858

Tierra Amarilla  

1852 

Roosevelt County

18,018

2,449

Portales  

1903 

San Juan County

113,801

5,514

Aztec  

1887 

San Miguel County

30,126

4,717

Las Vegas 

1852 

Sandoval County

89,908

3,710

Bernalillo  

1903 

Santa Fe County

129,292

1,909

Santa Fe  

1852 

Sierra County

13,270

4,180

Truth Or Consequences  

1884 

Socorro County

18,078

6,647

Socorro  

1852 

Taos County

29,979

2,203

Taos  

1852 

Torrance County

16,911

3,345

Estancia  

1903 

Union County

4,174

3,830

Clayton  

1903 

Valencia County

66,152

1,068

Los Lunas  

1852