Track Trends
| Year | Start | End | Days | Races | Avg. Att. | Avg. Han. |
| 1966 | July 1 | September 12 | 54 | 505 | 5,467 | 263,053 |
| 1967 | June 30 | September 11 | 54 | 527 | 5,344 | 251,256 |
| 1968 | July 2 | September 16 | 57 | 532 | 5,377 | 257,627 |
| 1969 | June 27 | September 8 | 57 | 545 | 5,928 | 291,209 |
| 1970 | June 26 | September 14 | 60 | 603 | 4,652 | 275,612 |
| 1971 | May 29 | June 27 | 11 | 111 | 6,399 | 333,363 |
| July 2 | September 6 | 49 | 465 | 5,147 | 299,649 | |
| 1972 | May 27 | June 25 | 11 | 111 | 6,433 | 361,575 |
| June 30 | September 4 | 49 | 476 | 4,611 | 314,574 | |
| 1973 | May 19 | September 3 | 62 | 597 | 5,235 | 337,675 |
| 1974 | May 11 | September 30 | 92 | 875 | 4,056 | 296,161 |
| 1975 | May 10 | September 15 | 84 | 797 | 4,161 | 297,621 |
| 1976 | May 12 | September 13 | 88 | 857 | 3,946 | 301,210 |
| 1977 | May 11 | November 20 | 120 | 1,098 | 3,858 | 308,995 |
| 1978 | May 10 | November 12 | 119 | 1,078 | 3,448 | 302,501 |
| 1979 | May 9 | November 11 | 119 | 1,075 | 3,114 | 307,696 |
| 1980 | May 3 | November 9 | 119 | 1,080 | 3,231 | 323,301 |
| 1981 | May 2 | November 8 | 119 | 1,084 | 3,300 | 343,108 |
| 1982 | May 1 | November 7 | 120 | 1,083 | 3,058 | 299,741 |
| 1983 | May 7 | November 6 | 117 | 1,047 | 2,815 | 261,751 |