The field is this narrow because of Harvard

A football field is 160 feet wide — 53⅓ yards. It has been that since 1881, and it very nearly wasn't.

Where the number came from

The width was set in 1881, following the 1880 changes that cut teams from fifteen players a side to eleven and introduced the system of downs. Fewer players needed less grass; American football narrowed away from its rugby inheritance.

The 1906 near-miss

When the rules committee met to make football safer and more open after the 1905 crisis, one proposal was simply to widen the field. More space, fewer collisions, more room for the newly legal forward pass.

Harvard had just poured concrete. Concrete beats rulebooks.

Harvard had recently built the first reinforced concrete stadium in the world, dimensioned for the existing field. You cannot widen a field inside a fixed concrete bowl, and the rulemakers needed Harvard on board. The proposal died.

What we got instead

Because the field could not get wider, the 1906 committee opened the game up a different way — by legalising the forward pass. It is a strange thought that the single most defining feature of American football may exist partly because one university had already poured its stands.