A fascinating aspect of this question is that the two most recently ratified amendments represent both the fastest and slowest examples. In 1971 it took only 99 days for the people to nullify a controversial and deeply divided court decision. Then in 1992 after lying open for 74003 days (202 years), one of the original elements of the bundle included with the Bill of Rights was ratified.
The Date Approved is when Congress (or a constitutional convention) voted to by a 2/3 majority to send the amendment to the States for ratification. The Date Ratified is when the 3/4 (of the States) quota had been reached. The dates are given in YYYY/MM/DD format for ease of comparison.
| Amendment Number |
Date Approved | Date Ratified | Elapsed Time |
|---|---|---|---|
| 1..10 | 1789/09/25 | 1791/12/15 | 811 days |
| 11 | 1794/03/04 | 1795/02/07 | 340 days |
| 12 | 1803/12/09 | 1804/06/15 | 188 days |
| 13 | 1865/01/31 | 1865/12/06 | 309 days |
| 14 | 1866/06/13 | 1868/07/09 | 757 days |
| 15 | 1869/02/26 | 1870/02/03 | 342 days |
| 16 | 1909/07/12 | 1913/02/03 | 1302 days |
| 17 | 1912/05/13 | 1913/04/08 | 330 days |
| 18 | 1917/12/18 | 1919/01/16 | 394 days |
| 19 | 1919/06/04 | 1920/08/18 | 441 days |
| 20 | 1932/03/02 | 1933/01/23 | 327 days |
| 21 | 1933/02/20 | 1933/12/05 | 288 days |
| 22 | 1947/03/21 | 1951/01/27 | 1408 days |
| 23 | 1960/06/17 | 1961/03/29 | 285 days |
| 24 | 1962/08/27 | 1964/01/23 | 514 days |
| 25 | 1965/07/06 | 1967/02/10 | 584 days |
| 26 | 1971/03/23 | 1971/07/01 | 99 days |
| 27 | 1789/09/25 | 1992/05/07 | 74003 days |