The Corcoran Surname Distribution Map shows all of the Corcorans (in yellow) documented in County Mayo, Ireland when the Griffith's Valuation was conducted between 1855 and 1857. Corcorans were noted in 33 different Civil Parishes in County Mayo at that time.
| 1. Achill | 2. Addergoole | 3. Aghagower |
| 4. Aghamore | 5. Aglish | 6. Annagh |
| 7. Ardagh | 8. Attymass | 9. Balla |
| 10. Ballinchalla | 11. Ballinrobe | 12. Ballintober |
| 13. Ballyhean | 14. Ballynahaglish | 15. Ballyovey |
| 16. Ballysakeery | 17. Bekan | 18. Bohola |
| 19. Breaghwy | 20. Burriscarra | 21. Burrishoole |
| 22. Cong | 23. Crossboyne | 24. Crossmolina |
| 25. Doonfeeny | 26. Drum | 27. Islandeady |
| 28. Kilbeagh | 29. Kilbelfad | 30. Kilbride |
| 31. Kilcolman | 32. Kilcommon | 33. Kilconduff |
| 34. Kilcummin | 35. Kildacommoge | 36. Kilfian |
| 37. Kilgarvan | 38. Kilgeever | 39. Killala |
| 40. Killasser | 41. Killedan | 42. Kilmaclasser |
| 43. Kilmainebeg | 44. Kilmainemore | 45. Kilmeena |
| 46. Kilmolara | 47. Kilmore | 48. Kilmoremoy |
| 49. Kilmovee | 50. Kilturra | 51. Kilvine |
| 52. Knock | 53. Lacken | 54. Manulla |
| 55. Mayo | 56. Meelick | 57. Moorgagagh |
| 58. Moygawnagh | 59. Oughaval | 60. Rathreagh |
| 61. Robeen | 62. Rosslee | 63. Shrule |
| 64. Tagheen | 65. Templemore | 66. Templemurry |
| 67. Toomore | 68. Touaghty | 69. Turlough |
| A. Castlemore (transferred to Co. Roscommon 1898) | B. Kilcolman, Costello Barony (Transferred to Co. Roscommon 1898) |