Table 1. Population and housing dynamics between 1990 and 2000 in Puerto Rico based on barrio type and elevation regions Barrio type and Elevation region n barrios Population in 1990 Population in 2000 Population change New households units People/housing units number % number % number % number % change 1990 2000 Urban 145 1 614 644 46.6 1 602 507 42.7 - 12 137 -0.8 69 668 12.0 3.17 2.81 Coastal plains 121 1 462 310 42.2 1 449 918 38.7 -12 392 -0.8 63 162 12.1 3.15 2.79 Coastal hills 14 113 112 3.3 115 676 3.1 2 564 2.3 5 702 13.7 3.44 3.09 Central mountains 10 39 222 1.1 36 913 1.0 - 2 309 -5.9 804 3.5 2.94 2.67 Suburban 375 1 416 001 40.8 1 651 349 44.0 235 348 16.6 108 842 30.1 3.91 3.51 Coastal plains 204 826 946 23.9 972 120 25.9 145 174 17.6 63 873 29.3 3.79 3.45 Coastal hills 115 396 690 11.4 459 200 12.2 62 510 15.8 30 486 31.3 4.07 3.59 Central mountains 56 192 365 5.5 220 029 5.9 27 664 14.4 14  483 31.2 4.15 3.61 Rural 360 436 250 12.6 497 166 13.3 60  916 14.0 30 467 23.2 3.58 3.31 Coastal plains 73 104 857 3.0 122 720 3.3 17 863 17.0 7 667 23.3 3.38 3.21 Coastal hills 110 141 247 4.1 165 403 4.4 24 156 17.1 10 907 27.3 3.66 3.37 Central mountains 177 190 146 5.5 209 043 5.6 18 897 9.9 11 893 20.1 3.65 3.34 TOTAL: 880 3 466 895 100 3 751 022 100 284 127 8.2 208 977 19.9 3.49 3.15