NFL field markings
From what I’ve gathered using images found online, the yard markings in most National Football League stadiums appear to be set in a Clarendon Bold or Black, or some modification thereof. (The zero, for example, is wider than you’ll see in most fonts to balance it with the width of the number to its left.)
It’s not clear when this standard was set and how strict the NFL is about it. There is no mention of the yard markings in the online rule book. I welcome football fans to weigh in with their knowledge on the subject.
Update (via Jeff Kellem): A Smithsonian magazine article on the NFL field design says there is no official standard:
According to official NFL rules, 30-foot deep scoring end zones bookend the field, which is demarcated by horizontal lines every five yards, with two-yard-long numbers indicating yard lines in multiples of 10 placed exactly twelve yards in from the sideline. Their font, surprisingly, isn’t officially standardized.
Update, Feb. 7, 2016: During 2015, to celebrate Super Bowl 50, every stadium had a gold 50-yard line marker. The style was also used today for the Super Bowl 50 field itself. These numbers appear to be based on a Century, not Clarendon.
Many fields use numbers based on Clarendon.
Officially mandated details of a professional football field. The size and spacing of the yard line numbers is specified, but not the lettering style.
To celebrate Super Bowl 50, during 2015 every stadium had a gold “50” at the 50-yard line.
Super Bowl 50 field.
Watching the Eagles-Texans game and note that the field numbers are of a different style to those we had at the London fixtures