context: Harvard's athletic rivalry with Yale is intense in every sport in which they meet, coming to a climax each fall in the annual football meeting, which dates back to 1875 and is usually called simply "The Game". While Harvard's football team is no longer one of the country's best as it often was a century ago during football's early days (it won the Rose Bowl in 1920), both it and Yale have influenced the way the game is played. In 1903, Harvard Stadium introduced a new era into football with the first-ever permanent reinforced concrete stadium of its kind in the country. The stadium's structure actually played a role in the evolution of the college game. Seeking to reduce the alarming number of deaths and serious injuries in the sport, Walter Camp (former captain of the Yale football team), suggested widening the field to open up the game. But the stadium was too narrow to accommodate a wider playing surface. So, other steps had to be taken. Camp would instead support revolutionary new rules for the 1906 season. These included legalizing the forward pass, perhaps the most significant rule change in the sport's history.
question: Which came later, legalizing the forward pass or Harvard Stadium becoming the first-ever permanent reinforced concrete stadium?