text: History Hajdú–Bihar county was created after World War II from the pre-1938 counties Hajdú and Bihar. See the articles of those counties for the history before World War II.
  Demographics
  In 2015, it had a population of 537,268 and the population density was 87/km2.
  Ethnicity
  The main minority populations in the county are Roma (about 18,000), Romanian (about 2,000), and German (about 1,000).
  Total population (2011 census): 546,721
  Ethnic groups (2011 census):
  Hungarians: 461,809 (95.05%)
  Romani: 18,132 (3.73%)
  Others and indefinable: 5,936 (1.22%)
  About 77,000 people in Hajdú-Bihar County did not declare their ethnicity during the 2011 census.
  Religion
  Religious adherence in the county according to 2011 census:
  Reformed – 158,513;
  Catholic – 86,084 (Roman Catholic – 53,697; Greek Catholic – 32,359);
  Evangelical – 1,086;
  Orthodox – 862;
  other religions – 10,330;
  Non-religious – 147,001;
  Atheism – 6,416;
  Undeclared – 136,429.
  Regional structure
  Economy
  Infrastructure
  Highways no. 4, 33, 35, 42 and 47 lead to the county and the county can also be reached Hajdú–Bihar via the M3 motorway (this motorway is now a spur to Debrecen). The total length of the public roads in the county is 1,511 km. 122 road bridges span the rivers and canals. The roads cross the national borders to Romania at the cities of Ártánd and Nyírábrány.
  Politics