Source: http://timclayton.photoshelter.com.MetLife Stadium photos by Tim Clayton. License: All Rights Reserved.
From what I've gathered using images found online, the yard markings in most National Football League stadiums appear to be set in aClarendonBold 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 theCentury, not Clarendon.
Source: http://timclayton.photoshelter.com.MetLife Stadium photos by Tim Clayton. License: All Rights Reserved.
Many fields use numbers based on Clarendon.
Source: http://timclayton.photoshelter.com.MetLife Stadium photos by Tim Clayton. License: All Rights Reserved.
Source: http://operations.nfl.com.©2015 NFL. License: All Rights Reserved.
Officially mandated details of a professional football field. The size and spacing of the yard line numbers is specified, but not the lettering style.
Source: http://ftw.usatoday.com.License: All Rights Reserved.
To celebrate Super Bowl 50, during 2015 every stadium had a gold "50" at the 50-yard line.
Source: http://mmqb.si.com.License: All Rights Reserved.
Super Bowl 50 field.
