1921 Census of England and Wales, General Report with Appendices, Table 88 : " Proportion per 1,000 persons aged 3 years and over in respect of whom Language Statements were returned".

  Total Welsh
Speakers.		 Welsh only. Both English
and Welsh.		 English only. Total English
speakers.
1921. 1911. 1921. 1911. 1921. 1911. 1921. 1911. 1921. 1911.
Wales and Monmouth 387 447 66 87 321 360 613 553 934 913
                     
Counties:—                    
  Anglesey 878 913 321 373 557 540 122 87 679 627
  Cardigan 868 912 276 348 592 564 132 88 724 652
  Carmarthen 845 864 169 209 676 655 155 136 831 791
  Merioneth 843 921 305 374 538 547 157 79 695 626
  Carnarvon 765 875 267 364 498 511 235 125 733 636
  Denbigh 510 576 90 103 420 473 490 424 910 897
  Montgomery 433 453 91 108 342 345 567 547 909 892
  Brecknock 399 421 48 57 351 364 601 579 952 943
  Flint 350 432 25 35 325 397 650 568 975 965
  Glamorgan 331 393 23 32 308 361 669 607 977 968
  Pembroke 314 332 60 79 254 253 686 668 940 921
  Radnor 66 55 5 1 61 54 934 945 995 999
  Monmouth 66 100 2 4 64 96 934 900 998 996
                     
Large Towns:—                    
  Aberdare U.D. 590 652 46 66 544 586 410 348 954 934
  Rhondda U.D. 488 562 32 45 456 517 512 438 968 955
  Merthyr Tydfil C.B 425 511 24 36 401 475 575 489 976 964
  Swansea C.B 291 * 17 * 274 * 709 * 983 *
  Cardiff, City of, C.B. 52 70 3 2 49 68 948 930 997 998
  Newport C.B. 21 27 0 0 21 27 979 973 1000 1000

* Figures not available.