| Date | Transaction |
| 02-28-1975 | John Dempsey has retired from football. |
| 09-01-1974 | The Denver Dawgs have waived John Dempsey. |
| 08-05-1974 | The Denver Dawgs have moved Ed Coghill to the active roster. The Denver Dawgs have moved John Dempsey to the inactive roster. |
| 09-17-1972 | John Dempsey of the Denver Dawgs is injured with a shoulder muscle strain and is expected to be out for approximately 8 days. |
| 09-04-1972 | The Denver Dawgs have moved Frank Smith, Marty Oliver, John Dempsey, and Theo Adams to the active roster. The Denver Dawgs have moved Ron Schleicher, Rob Rudnick, Bob Knox, and Antico Griffith to the inactive roster. |
| 08-07-1972 | The Denver Dawgs have moved Erik Sands, Irving DeGrenier, Ron Schleicher, Rob Rudnick, John Cordileone, Wendell Jackson, John Riley, Jim Goldberg, Jim McJulien, Frank Morgan, Bob Knox, Mike Crittenden, Antico Griffith, Bill Collins, Drew Chipley, and Bob Lott to the active roster. The Denver Dawgs have moved Justin Hower, Brian Bolden, Ed Anderson, Bud Mangum, Matt Perry, Hal "Jackie" Gleason, Earl Dupree, Rosevelt McCullough, Frank Smith, Marty Oliver, Larry Spiers, John Dempsey, Hal Grabowski, Theo Adams, Herbert Daney, and Travares Niland to the inactive roster. |
| 10-17-1971 | John Dempsey of the Denver Dawgs is injured with a hip contusion and is expected to be out for approximately 10 days. |
| 08-23-1971 | The Denver Dawgs have moved John Dempsey to the active roster. |
| 08-09-1971 | The Denver Dawgs have moved John Whittington and Irving DeGrenier to the active roster. The Denver Dawgs have moved John Dempsey and Hal Grabowski to the inactive roster. |
| 10-25-1970 | John Dempsey of the Denver Dawgs is injured with a partial ACL tear and is expected to be out for approximately 32 days. |
| 09-07-1970 | The Denver Dawgs have removed John Dempsey from the trade block. |
| 08-24-1970 | The Denver Dawgs have moved Justin Hower, Marty Oliver, John Dempsey, and Ed Anderson to the active roster. The Denver Dawgs have moved Tommy Jenkins, John Whittington, Wayne Gretzky, and Les Burt to the inactive roster. |
| 08-24-1970 | The Denver Dawgs have placed John Dempsey on the trade block. |
| 08-10-1970 | The Denver Dawgs have moved John Whittington, Lou Bass, and Willie Young to the active roster. The Denver Dawgs have moved Marv Lewis, Hal Grabowski, and John Dempsey to the inactive roster. |
| 08-19-1968 | The Denver Dawgs have moved John Dempsey and Marv Lewis to the active roster. The Denver Dawgs have moved Bobby Reyes and Hal Grabowski to the inactive roster. |
| 12-18-1967 | The Denver Dawgs have moved Warren Miles, Les Burt, Bob Montgomery, Tony Goodspeed, and Theo Adams to the active roster. The Denver Dawgs have moved Johnny Settle, Marty Oliver, John Dempsey, Buddy Harris, and Hank Jones to the inactive roster. |
| 08-28-1967 | The Denver Dawgs have moved Willie Smith, Henry Bell, Marty Oliver, Bobby Reyes, John Dempsey, and Buddy Harris to the active roster. The Denver Dawgs have moved Marv Lewis, Warren Miles, Les Burt, Bob Montgomery, Tony Goodspeed, and Theo Adams to the inactive roster. |
| 08-13-1967 | Trade #46070 has been completed between the Minnesota Wolves and the Denver Dawgs. The Denver Dawgs receive Reggie Maple (RB), John Dempsey (WR) from the Minnesota Wolves in exchange for Draft Pick - 1969 Round 2 (DEN), Draft Pick - 1970 Round 4 (DEN). |
| 10-03-1966 | The Minnesota Wolves have moved John Dempsey to the active roster. The Minnesota Wolves have moved Byron Gaines to the inactive roster. |
| 09-19-1966 | The Minnesota Wolves have moved Chet Samuel to the active roster. The Minnesota Wolves have moved John Dempsey to the inactive roster. |
| 09-18-1966 | John Dempsey of the Minnesota Wolves is injured with a foot ligament sprain and is expected to be out for approximately 13 days. |
| 09-08-1963 | John Dempsey of the Minnesota Wolves is injured with a rib fracture and is expected to be out for approximately 29 days. |
| 12-30-1962 | John Dempsey of the Minnesota Wolves is injured with a shoulder joint injury and is expected to be out for approximately 38 days. |
Wide Receiver