RANKING · 2010 CENSUS · 500 SHOWN OF 3,118

Largest Scotch-Irish population, US counties · 2010

US counties ranked by the number of residents who are Scotch-Irish ancestry, from the 2010 American Community Survey detailed-origin tables. Each list covers the full eligible universe; download the complete data as CSV. Los Angeles County, California leads at 66,233. 3,118 counties qualify in total. California carries 6 of the top 25 entries.

Scotch-Irish Americans: full group profile →

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SAME RANKING BYCities States Metros

RELATEDLargest American population Highest American population share Largest Arab population Highest Arab population share Largest Egyptian population Highest Egyptian population share

YEAR2010 2020 2024

RANKPLACESTATEPOPSCOTCH-IRISH POPULATIONVS –

USUnited States1.7% of US population308,745,5385,227,821–

01Los Angeles County, CACA9,694,93466,233–

02Maricopa County, AZAZ4,689,55857,427–

03Harris County, TXTX5,045,02647,747–

04San Diego County, CACA3,282,24846,116–

05King County, WAWA2,344,93942,412–

06Orange County, CACA3,149,50736,929–

07Mecklenburg County, NCNC1,233,38335,310–

08Tarrant County, TXTX2,248,46634,260–

09Cook County, ILIL5,194,62533,082–

10Dallas County, TXTX2,661,39730,921–

11Allegheny County, PAPA1,225,03530,257–

12Middlesex County, MAMA1,669,97929,903–

13Wake County, NCNC1,257,23528,676–

14Riverside County, CACA2,544,91625,005–

15Travis County, TXTX1,389,67023,308–

16Fairfax County, VAVA1,167,87323,149–

17Wayne County, MIMI1,769,03822,644–

18Oakland County, MIMI1,288,33721,568–

19Sacramento County, CACA1,618,46021,377–

20Bexar County, TXTX2,160,08820,930–

21Clark County, NVNV2,407,22620,870–

22Franklin County, OHOH1,361,53620,404–

23Knox County, TNTN511,45320,397–

24San Bernardino County, CACA2,224,09120,035–

25Shelby County, TNTN910,22619,652–

26Hillsborough County, FLFL1,574,11519,289–

27Davidson County, TNTN745,90419,189–

28Snohomish County, WAWA870,65618,607–

29Pierce County, WAWA946,28818,536–

30Jefferson County, ALAL665,74217,789–

31Pima County, AZAZ1,074,68517,672–

32Duval County, FLFL1,062,96317,635–

33Multnomah County, OROR795,39117,607–

34Pinellas County, FLFL948,56317,593–

35Alameda County, CACA1,636,63016,795–

36Santa Clara County, CACA1,914,39116,315–

37Guilford County, NCNC562,23416,167–

38Suffolk County, NYNY1,546,09015,856–

39Greenville County, SCSC583,12515,852–

40Contra Costa County, CACA1,170,07015,795–

41Norfolk County, MAMA739,74915,734–

42Cobb County, GAGA793,34515,652–

43St. Louis County, MOMO990,91115,637–

44Plymouth County, MAMA546,82915,330–

45Fulton County, GAGA1,098,79115,280–

46Denton County, TXTX1,069,34615,187–

47Collin County, TXTX1,297,17915,155–

48Cuyahoga County, OHOH1,232,92515,009–

49Buncombe County, NCNC277,41714,972–

50Palm Beach County, FLFL1,575,72614,866–

51Orange County, FLFL1,528,00214,708–

52Essex County, MAMA826,65314,576–

53Gwinnett County, GAGA1,018,09914,528–

54El Paso County, COCO757,04014,494–

55Worcester County, MAMA888,50214,157–

56Montgomery County, PAPA877,64314,136–

57Jefferson County, KYKY795,22213,841–

58Oklahoma County, OKOK822,12513,654–

59Jackson County, MOMO732,99413,485–

60Johnson County, KSKS636,90613,416–

61Jefferson County, COCO580,45113,390–

62Montgomery County, MDMD1,074,58213,267–

63Broward County, FLFL2,013,31713,260–

64Hennepin County, MNMN1,284,78413,219–

65New York County, NYNY1,664,86213,158–

66York County, SCSC306,88712,825–

67Macomb County, MIMI886,22112,603–

68Chester County, PAPA557,11612,559–

69Salt Lake County, UTUT1,220,91612,502–

70Washington County, OROR611,70812,300–

71Marion County, ININ992,19612,209–

72Spokane County, WAWA558,34412,102–

73Ventura County, CACA830,85112,033–

74Richland County, SCSC434,95611,933–

75Polk County, FLFL874,79011,854–

76DeKalb County, GAGA774,39411,839–

77Brevard County, FLFL663,98211,809–

78Tulsa County, OKOK698,78211,724–

79Bucks County, PAPA647,82811,692–

80Clark County, WAWA532,11911,485–

81Baltimore County, MDMD847,65011,484–

82Westmoreland County, PAPA349,32411,476–

83Washington County, PAPA210,80211,333–

84DuPage County, ILIL934,29811,280–

85Charleston County, SCSC436,20011,151–

86Forsyth County, NCNC401,71811,110–

87Sonoma County, CACA486,44411,108–

88Bernalillo County, NMNM667,60111,097–

89Virginia Beach, VAVA453,73710,850–

90Hamilton County, OHOH838,41810,796–

91Spartanburg County, SCSC380,85710,794–

92Hamilton County, TNTN390,83310,678–

93Anne Arundel County, MDMD603,38010,630–

94Cumberland County, MEME317,22210,604–

95Arapahoe County, COCO673,82010,379–

96Erie County, NYNY946,74110,370–

97Montgomery County, TXTX781,19410,307–

98Denver County, COCO740,61310,302–

99Lee County, FLFL875,60710,223–

100Clackamas County, OROR426,28010,211–

101Summit County, OHOH538,37610,172–

102Kern County, CACA927,0689,938–

103Mobile County, ALAL411,6589,934–

104Delaware County, PAPA580,9379,926–

105Lancaster County, PAPA563,1599,923–

106New Hanover County, NCNC245,9599,848–

107Philadelphia County, PAPA1,574,2819,813–

108Sedgwick County, KSKS538,4339,797–

109Cumberland County, NCNC338,4739,783–

110Williamson County, TXTX752,8279,761–

111Monroe County, NYNY750,5069,722–

112Gaston County, NCNC246,5589,583–

113Volusia County, FLFL606,5739,577–

114Hillsborough County, NHNH433,4159,403–

115Madison County, ALAL433,5169,347–

116New Castle County, DEDE588,0269,291–

117Lexington County, SCSC317,5889,197–

118Fresno County, CACA1,035,4569,106–

119Lane County, OROR381,5849,059–

120Chesterfield County, VAVA397,1489,050–

121Nassau County, NYNY1,398,9398,938–

122Williamson County, TNTN272,0618,924–

123Washoe County, NVNV509,3868,897–

124Fayette County, KYKY329,7518,882–

125Montgomery County, OHOH539,5988,851–

126Pasco County, FLFL674,5168,840–

127York County, PAPA473,1978,820–

128Monmouth County, NJNJ651,0358,790–

129Kent County, MIMI675,2328,751–

130Butler County, PAPA200,1698,629–

131Pulaski County, ARAR404,6118,604–

132East Baton Rouge Parish, LALA456,1808,525–

133San Francisco County, CACA826,0798,480–

134Douglas County, NENE606,4608,463–

135Seminole County, FLFL491,8848,428–

136Sarasota County, FLFL479,9588,377–

137Union County, NCNC267,6748,271–

138Ada County, IDID546,1418,235–

139Kitsap County, WAWA283,3748,013–

140Lake County, ILIL719,3397,975–

141Cabarrus County, NCNC249,7257,935–

142Henrico County, VAVA342,7757,908–

143Stark County, OHOH373,7717,885–

144Will County, ILIL712,2537,827–

145Anderson County, SCSC219,9307,789–

146Rockingham County, NHNH324,0777,783–

147Horry County, SCSC427,5517,783–

148Boulder County, COCO328,5607,774–

149Escambia County, FLFL333,8347,769–

150Larimer County, COCO377,2927,741–

151Blount County, TNTN143,8207,739–

152Durham County, NCNC347,2407,703–

153Rutherford County, TNTN386,3527,682–

154Onondaga County, NYNY466,5847,595–

155Iredell County, NCNC211,7987,509–

156Sullivan County, TNTN163,7597,474–

157Cherokee County, GAGA299,2737,445–

158Leon County, FLFL299,0487,381–

159San Mateo County, CACA743,5687,378–

160Ocean County, NJNJ673,7467,367–

161Bristol County, MAMA593,6407,335–

162Suffolk County, MAMA791,8917,332–

163Santa Barbara County, CACA442,0657,268–

164Utah County, UTUT759,8597,249–

165Shelby County, ALAL238,5527,241–

166Bergen County, NJNJ977,0267,161–

167Orange County, NCNC152,4986,998–

168Erie County, PAPA265,8326,961–

169Penobscot County, MEME157,9676,932–

170York County, MEME222,4346,926–

171St. Charles County, MOMO426,4996,890–

172San Joaquin County, CACA823,8156,866–

173San Luis Obispo County, CACA282,3676,839–

174Washtenaw County, MIMI370,2146,834–

175Kanawha County, WVWV172,3816,830–

176Genesee County, MIMI401,0936,794–

177Stanislaus County, CACA557,7196,770–

178Prince William County, VAVA502,9666,765–

179Westchester County, NYNY1,015,7436,751–

180Placer County, CACA442,0816,747–

181Anchorage, AKAK287,1556,714–

182Polk County, IAIA516,5466,677–

183Honolulu County, HIHI988,7036,667–

184Beaver County, PAPA166,0326,654–

185Greene County, MOMO309,2866,652–

186Douglas County, COCO399,3966,639–

187Cumberland County, PAPA277,2706,611–

188Loudoun County, VAVA449,7496,523–

189Providence County, RIRI678,1796,498–

190Thurston County, WAWA304,2616,498–

191Adams County, COCO554,6686,414–

192Alamance County, NCNC186,1776,384–

193Henderson County, NCNC122,3756,347–

194Burlington County, NJNJ481,4396,335–

195Butte County, CACA209,2116,323–

196Marion County, FLFL442,6606,306–

197Marion County, OROR355,7776,297–

198Alachua County, FLFL290,0286,268–

199Lake County, FLFL456,0686,144–

200Lubbock County, TXTX328,9066,143–

201Kings County, NYNY2,653,9636,090–

202Collier County, FLFL417,1316,071–

203Monterey County, CACA433,7296,053–

204Miami-Dade County, FLFL2,802,0296,053–

205Rowan County, NCNC155,0966,025–

206Camden County, NJNJ535,7995,991–

207Hampden County, MAMA464,3385,971–

208Dane County, WIWI590,3755,919–

209Sumner County, TNTN215,5385,914–

210Kane County, ILIL525,7575,913–

211Galveston County, TXTX372,2075,908–

212District of Columbia, DCDC693,6455,907–

213Morris County, NJNJ524,2515,888–

214Florence County, SCSC138,5045,842–

215Baldwin County, ALAL267,7615,814–

216Bell County, TXTX402,2485,787–

217Manatee County, FLFL468,2005,773–

218Pinal County, AZAZ539,3805,768–

219Butler County, OHOH400,1285,738–

220Jackson County, OROR221,7955,735–

221Marin County, CACA253,6945,711–

222Whatcom County, WAWA236,3925,677–

223Fort Bend County, TXTX975,1915,668–

224Frederick County, MDMD302,8835,618–

225Pickens County, SCSC139,1985,612–

226Brazoria County, TXTX419,0805,612–

227Rankin County, MSMS162,1815,507–

228Ramsey County, MNMN541,6235,433–

229Yavapai County, AZAZ252,5525,404–

230Milwaukee County, WIWI924,2165,355–

231Dauphin County, PAPA293,3515,353–

232Arlington County, VAVA243,9315,275–

233Santa Rosa County, FLFL211,1155,258–

234Lawrence County, PAPA83,9115,256–

235Solano County, CACA455,3765,248–

236Brazos County, TXTX249,0885,182–

237Cleveland County, OKOK303,9735,157–

238Haywood County, NCNC63,3695,092–

239Mercer County, PAPA107,8605,091–

240Harford County, MDMD266,4465,079–

241Clay County, MOMO265,0325,071–

242Lorain County, OHOH323,2195,015–

243Caddo Parish, LALA224,2265,006–

244Catawba County, NCNC170,1724,979–

245Santa Cruz County, CACA258,8524,963–

246Lake County, OHOH232,2174,962–

247Chesapeake, VAVA255,3324,910–

248McLennan County, TXTX272,0204,883–

249Hinds County, MSMS211,8884,876–

250Middlesex County, NJNJ883,3354,876–

251Harnett County, NCNC150,1374,876–

252Nueces County, TXTX352,9924,827–

253Ingham County, MIMI289,7094,762–

254Clay County, FLFL239,5934,755–

255Barnstable County, MAMA233,5394,710–

256Kennebec County, MEME129,0674,695–

257Prince George's County, MDMD970,3744,694–

258Washington County, TNTN141,1994,684–

259Lake County, ININ504,6124,669–

260Davidson County, NCNC180,1824,656–

261Lancaster County, NENE334,0494,615–

262Queens County, NYNY2,358,1824,602–

263Washington County, ARAR271,2134,593–

264Bay County, FLFL204,4794,590–

265St. Johns County, FLFL346,3284,572–

266Boone County, MOMO191,7464,542–

267Weld County, COCO378,4264,532–

268Harrison County, MSMS217,1364,522–

269Brunswick County, NCNC174,7024,506–

270El Dorado County, CACA192,3234,490–

271Gloucester County, NJNJ312,6384,483–

272Tuscaloosa County, ALAL241,3684,479–

273Madison County, ILIL263,1104,475–

274Deschutes County, OROR213,0724,473–

275Hamilton County, ININ387,0364,467–

276Shasta County, CACA181,6484,460–

277Berks County, PAPA440,0724,456–

278Okaloosa County, FLFL221,8104,440–

279Dakota County, MNMN457,7104,425–

280Richmond, VAVA237,2574,401–

281Merrimack County, NHNH158,0784,372–

282Lucas County, OHOH423,3474,371–

283Orange County, NYNY417,6694,366–

284Berkeley County, SCSC274,6664,346–

285Mohave County, AZAZ228,1024,344–

286Onslow County, NCNC217,1754,333–

287Chatham County, GAGA311,8554,317–

288Lee County, ALAL189,8814,305–

289Smith County, TXTX252,5494,300–

290DeSoto County, MSMS197,9184,297–

291Shawnee County, KSKS178,6074,270–

292Allen County, ININ402,3294,257–

293Pitt County, NCNC182,9364,247–

294Dutchess County, NYNY300,7084,218–

295Franklin County, PAPA160,6524,214–

296Kalamazoo County, MIMI263,7954,211–

297Montgomery County, ALAL225,8914,183–

298Benton County, ARAR332,5544,183–

299Sevier County, TNTN101,3424,182–

300Howard County, MDMD339,1834,163–

301Johnston County, NCNC256,4484,155–

302Roanoke County, VAVA97,1504,137–

303Albany County, NYNY321,2254,121–

304Livingston County, MIMI197,3154,112–

305Sangamon County, ILIL194,1704,110–

306St. Tammany Parish, LALA279,1084,104–

307Baltimore, MDMD569,9974,103–

308Hays County, TXTX304,3904,096–

309Yolo County, CACA224,4104,094–

310McHenry County, ILIL317,7514,074–

311Beaufort County, SCSC204,4334,047–

312Randolph County, NCNC149,5164,014–

313St. Joseph County, ININ272,8613,995–

314Albemarle County, VAVA118,3563,991–

315Roanoke, VAVA99,1113,985–

316Norfolk, VAVA231,0133,980–

317Forsyth County, GAGA282,8053,939–

318Davis County, UTUT381,2273,928–

319Jefferson County, TXTX254,3213,901–

320Kootenai County, IDID191,8643,856–

321Moore County, NCNC110,6193,845–

322Monroe County, ININ143,3453,759–

323Hanover County, VAVA116,4233,750–

324Humboldt County, CACA131,6473,744–

325Jefferson Parish, LALA431,3983,743–

326Mahoning County, OHOH224,7063,735–

327Burke County, NCNC88,6553,721–

328El Paso County, TXTX877,8583,717–

329Mercer County, NJNJ399,2893,716–

330Chittenden County, VTVT169,1153,687–

331Indiana County, PAPA82,8783,673–

332St. Lucie County, FLFL402,4493,668–

333Waukesha County, WIWI417,2103,647–

334Saratoga County, NYNY241,3433,641–

335Trumbull County, OHOH198,9723,638–

336Henry County, GAGA264,9223,629–

337St. Clair County, MIMI160,4863,614–

338Aiken County, SCSC181,5153,613–

339Columbiana County, OHOH99,3773,602–

340Alexandria, VAVA160,6623,602–

341Parker County, TXTX184,7673,594–

342Kenton County, KYKY175,7793,575–

343Hampshire County, MAMA164,0653,568–

344Mesa County, COCO162,8453,551–

345Essex County, NJNJ896,3793,548–

346Indian River County, FLFL172,7993,543–

347Jackson County, MSMS147,6663,539–

348Lehigh County, PAPA384,3833,516–

349Augusta County, VAVA78,9403,507–

350Nevada County, CACA101,9113,499–

351Delaware County, OHOH242,0323,495–

352Linn County, IAIA232,0283,479–

353Monongalia County, WVWV107,9913,475–

354Montgomery County, TNTN249,9353,442–

355Montgomery County, VAVA98,4343,423–

356Wilson County, TNTN175,0333,411–

357Taylor County, TXTX150,0773,395–

358Martin County, FLFL166,2723,391–

359Northampton County, PAPA324,4113,388–

360Warren County, OHOH257,1813,368–

361Jefferson County, MOMO233,1323,365–

362Ouachita Parish, LALA158,5423,364–

363Portage County, OHOH163,4043,355–

364Fayette County, GAGA125,1563,335–

365Cleveland County, NCNC103,3253,333–

366Bradley County, TNTN115,4653,326–

367Crawford County, PAPA81,7923,325–

368Citrus County, FLFL171,6663,320–

369Union County, NJNJ601,8633,310–

370Greene County, OHOH174,3223,287–

371Licking County, OHOH185,5643,286–

372Watauga County, NCNC54,7863,266–

373Anderson County, TNTN82,0663,266–

374Muscogee County, GAGA202,1713,256–

375Hernando County, FLFL221,7013,251–

376Androscoggin County, MEME116,4873,234–

377Hall County, GAGA226,5683,223–

378Charlotte County, FLFL217,2123,222–

379Yakima County, WAWA259,1853,209–

380Blair County, PAPA119,5413,208–

381Morgan County, ALAL126,4833,200–

382Douglas County, OROR111,9513,197–

383Winnebago County, ILIL283,6743,193–

384Cabell County, WVWV91,1833,191–

385Missoula County, MTMT123,5133,185–

386Washington County, RIRI129,7953,159–

387Dorchester County, SCSC178,3973,153–

388Jackson County, MIMI159,5523,150–

389McLean County, ILIL171,4193,149–

390Comal County, TXTX209,1663,142–

391Navajo County, AZAZ109,9463,138–

392Johnson County, TXTX218,0483,136–

393Weber County, UTUT278,1743,131–

394Rutherford County, NCNC65,7453,128–

395Clarke County, GAGA129,9213,120–

396Linn County, OROR132,8433,118–

397Centre County, PAPA157,3933,115–

398Lancaster County, SCSC114,2963,110–

399Newport News, VAVA183,2303,100–

400Ellis County, TXTX240,8673,096–

401Clermont County, OHOH216,9773,090–

402St. Clair County, ILIL250,7083,068–

403Benton County, WAWA221,7223,067–

404Sussex County, DEDE277,1403,058–

405Calcasieu Parish, LALA208,4663,054–

406Carroll County, MDMD176,6773,054–

407Yellowstone County, MTMT172,6923,052–

408Strafford County, NHNH135,0433,050–

409Kent County, DEDE194,7863,036–

410Passaic County, NJNJ531,6243,030–

411Spotsylvania County, VAVA155,3883,024–

412Cowlitz County, WAWA114,8853,010–

413Jackson County, NCNC45,0393,007–

414Canyon County, IDID275,1233,005–

415St. Louis, MOMO278,1443,000–

416Ottawa County, MIMI308,4592,990–

417Warren County, KYKY149,3752,988–

418Medina County, OHOH185,0252,972–

419Santa Fe County, NMNM156,9072,959–

420Tippecanoe County, ININ190,4562,944–

421Craven County, NCNC105,0252,935–

422Richmond County, GAGA206,5592,926–

423Champaign County, ILIL209,9722,924–

424Madison County, TNTN100,7902,910–

425Peoria County, ILIL178,5532,901–

426Somerset County, NJNJ356,4862,898–

427Garland County, ARAR99,6952,891–

428Anoka County, MNMN381,6052,891–

429Elmore County, ALAL91,5772,873–

430Oconee County, SCSC83,7752,870–

431Chatham County, NCNC85,1112,852–

432Marshall County, ALAL103,5372,846–

433Wayne County, NCNC122,2782,843–

434Greenwood County, SCSC70,3792,842–

435Tulare County, CACA485,1462,842–

436Saginaw County, MIMI187,6882,839–

437Broome County, NYNY195,7362,833–

438Kent County, RIRI173,4952,830–

439Lincoln County, NCNC98,6542,829–

440Clark County, OHOH135,3402,810–

441Ulster County, NYNY183,3302,805–

442Randall County, TXTX152,3512,799–

443Niagara County, NYNY208,9122,795–

444Porter County, ININ176,0492,783–

445Madison County, KYKY101,6962,780–

446Atlantic County, NJNJ278,6572,776–

447Laramie County, WYWY102,9382,767–

448Vanderburgh County, ININ181,9952,757–

449Hendricks County, ININ193,5102,756–

450Houston County, GAGA178,2142,748–

451Oneida County, NYNY226,3922,747–

452Stafford County, VAVA170,8032,743–

453St. Louis County, MNMN200,5182,729–

454Bossier Parish, LALA131,8672,714–

455Transylvania County, NCNC34,2112,712–

456Hawaii County, HIHI210,0432,712–

457Fayette County, PAPA123,0212,709–

458Grayson County, TXTX153,6132,708–

459Washington County, VAVA53,8982,694–

460Lauderdale County, ALAL97,1352,685–

461Guadalupe County, TXTX201,1112,682–

462Jasper County, MOMO127,4282,671–

463Tom Green County, TXTX120,6022,669–

464Douglas County, KSKS120,9202,664–

465Carteret County, NCNC70,4692,663–

466Orleans Parish, LALA362,1542,646–

467Coweta County, GAGA160,2402,638–

468Richland County, OHOH124,8932,632–

469Carter County, TNTN57,3612,622–

470Berkshire County, MAMA128,2242,619–

471Midland County, TXTX187,8552,604–

472Flathead County, MTMT115,4292,600–

473McDowell County, NCNC45,1982,600–

474Skagit County, WAWA132,9752,596–

475Matanuska-Susitna, AKAK118,6662,591–

476Faulkner County, ARAR133,9792,590–

477Pender County, NCNC72,1112,590–

478Rock Island County, ILIL141,8692,578–

479Hudson County, NJNJ735,0332,573–

480Washington County, MNMN286,8952,568–

481Paulding County, GAGA190,9962,565–

482Sebastian County, ARAR130,6412,558–

483Fairfield County, OHOH169,7522,544–

484Saline County, ARAR133,2882,537–

485Sandoval County, NMNM159,5652,535–

486Fairbanks North Star, AKAK93,9722,532–

487Tazewell County, ILIL130,0492,517–

488Napa County, CACA132,9492,512–

489Cambria County, PAPA128,9682,508–

490Caldwell County, NCNC81,1052,501–

491Berkeley County, WVWV139,5222,494–

492Armstrong County, PAPA63,6982,483–

493Cecil County, MDMD107,1312,475–

494Yamhill County, OROR110,0242,470–

495Cochise County, AZAZ126,3322,466–

496Elkhart County, ININ208,7742,457–

497Laurens County, SCSC71,8482,448–

498Luzerne County, PAPA332,1262,447–

499Comanche County, OKOK122,1582,441–

500Johnson County, ININ174,2622,434–

SHOWING 1–500 OF 3,118

Download CSV (full list, 3,118 rows)

UPDATED 2026-07-15 · DATA: US CENSUS BUREAU DECENNIAL CENSUS

Frequently asked

Which county has the highest scotch-irish population?

Los Angeles County, California ranks #1 with 66,233 (2010 Decennial Census).

What are the top 5 counties by scotch-irish population?

Los Angeles County, California, Maricopa County, Arizona, Harris County, Texas, San Diego County, California, King County, Washington.

How many counties are in this ranking?

3,118 counties qualify after filtering for population minimums and data availability. The ranking covers 2010 Decennial Census data.

How is scotch-irish population measured?

Number of residents who are Scotch-Irish ancestry (Ancestry, ACS detailed tables). Source: US Census Bureau, 2010 Decennial Census.