Domestic personnel includes both Civil Service and Foreign Service. Overseas personnel includes Foreign Service only.
| Year | Domestic | Overseas | Total |
| 1781 | 4 | 10 | 14 |
| 1790 | 8 | 20 | 28 |
| 1800 | 10 | 62 | 72 |
| 1810 | 9 | 56 | 65 |
| 1820 | 16 | 96 | 111 |
| 1830 | 23 | 153 | 176 |
| 1840 | 38 | 170 | 208 |
| 1850 | 22 | 218 | 240 |
| 1860 | 42 | 281 | 323 |
| 1870 | 65 | 804 | 869 |
| 1880 | 80 | 977 | 1,067 |
| 1890 | 76 | 1,105 | 1,181 |
| 1900 | 91 | 1,137 | 1,228 |
| 1910 | 234 | 1,043 | 1,277 |
| 1920 | 708 | 514 | 1,222 |
| 1930 | 714 | 633 | 1,347 |
| 1940 | 1,128 | 840 | 1,968 |
| 1950 | 8,609 | 7,710 | 16,319 |
| 1960 | 7,116 | 6,178 | 13,294 |
| 1970 | 6,983 | 5,865 | 12,848 |
| 1980 | 8,433 | 5,861 | 13,962 |
| 1990 | 10,063 | 6,783 | 16,846 |
| 1997 | 9,416 | 6,090 | 15,506 |