Chain crew - Wikipedia
Why the NFL Still Uses Chains to Measure First Downs
NFL chain gangs: Everything you need to know about the crews who man the down markers - Sports Illustrated
First-down spots limit the necessity for too many measurements – Football Zebras
Break the Chain: The USFL's Virtual 1st Down Measurements Are Working
NFL chain gangs: Everything you need to know about the crews who man the down markers - Sports Illustrated
Why the NFL Still Uses Chains to Measure First Downs
Ask Sam Farmer: Why does the NFL use just one set of first-down chains when they have two on the field? - Los Angeles Times
Cleveland Browns: What constitutes a first down in the NFL?
College fans might not notice new first-down clock rule, but some coaches are wary of its effect | AP News
Super Bowl LIV: How NFL Measures First Downs Is Primitively Low-Tech
NFL chain gangs: Everything you need to know about the crews who man the down markers - Sports Illustrated
Using a chip in the ball to measure first downs won't solve the NFL's problems - Sports Illustrated
Chain crew - Wikipedia
Why the NFL Still Uses Chains to Measure First Downs
Ball Placement - The Art & Science - Referee.com
Unchained? Technology exists if the NFL wants to measure first downs with precision | Broncos preview | Sports | gazette.com
Time to trade the NFL chains for lasers – The Denver Post
In Silicon Valley, a Time-Honored Sport Looks to the Future - The New York Times
/cdn.vox-cdn.com/uploads/chorus_image/image/58058933/ChainGangs_AP_Ringer.0.jpg "We Must Protect Football's Chain Gang at All Costs - The Ringer")
We Must Protect Football's Chain Gang at All Costs - The Ringer
/cdn.vox-cdn.com/uploads/chorus_image/image/71892475/1060182000.0.jpg "Broken 1st-down chain temporarily pauses Giants-Eagles Divisional Round game - SBNation.com")
Broken 1st-down chain temporarily pauses Giants-Eagles Divisional Round game - SBNation.com
:max_bytes(150000):strip_icc()/GettyImages-457406155-5663dc1e5f9b583dc376f8bf.jpg "The Chain Gang in Football - Role and Responsbilities")
The Chain Gang in Football - Role and Responsbilities
FORZA American Football Chain Set | Net World Sports
Unchained? Technology exists if the NFL wants to measure first downs with precision | Broncos preview | Sports | gazette.com
