America's Blitz is a colloquial term for the following blitz concept:
The blitz is known as America's Blitz because "every" team in America runs it. I have also heard the blitz called the NCAA Blitz. The name similarly implies that every college team runs this blitz. While not every team is running the blitz it is very common. Looking in a few NFL and college playbooks here are a few examples of the America's Blitz concept.
This example is from long time Pittsburgh Steeler defensive coordinator Dick Lebeau.
Here it is from Mark Dantonio's time as Ohio State's defensive coordinator. This variation of the concept is being run from a 3 man line sub personnel with multiple DB's in the game.
Another example of America's blitz from Coach Saban being run out of sub personnel Nickel or Dime.
Here from Bo Pelini's Nebraska Defense
From Rex Ryan's NY Jets Defense
It doesn't take long to see why this concept is known as America's Blitz.
Why is this blitz concept so ubiquitous? Simple answer it is effective. The deeper answer is versatility. This blitz concept can be run from nearly all base and sub defensive personnel groups. Defenses also have the flexibility to play man or zone coverage behind this blitz.
The blitz also has usage versatility. The blitz successfully attacks both run blocking schemes and pass protections. Defenses who carry this concept into a game plan can have confidence this blitz can be effectively called in multiple situations.
The success of the concept comes from the blitzes ability to overload half of the offense, attack the blocking scheme, and adjust based on the offense's blocking.
The concept is simple. The outside blitzer (Sam) is off the edge as a contain player. The DE to the blitz is slanting to the A gap. The inside blitzer (Mike) is letting the DE clear first and blitzing the B gap.
Several situations can play out based on the offensive blocking scheme.
The first situation is the offense zone blocks to the blitz. The zone could be either a zone run scheme or zone pass protection.
If the offense is disciplined in their zone blocking the offense has a blocker for each defender in each gap. In this situation the Sam, Mike, End, and Nose all have excellent gap leverage and the ability to shed blocks and make a play. This blitz challenges the offense to stay disciplined in their zone blocking.
The DE slanting to the A gap creates a conflict for the Guard. The Guard initially feels like the DE is attacking the B gap. In that case the Guard is responsible to block him. As the guard realizes the DE is actually slanting down to the A gap, it may be too late for the Guard to transition and make a good block on the blitzing Mike in the B gap.
The Center has a similar conflict. If the Center engages with the Nose at all, the Center's block on the DE slant to the A gap is very difficult.
Another situation is the OT blocks down on the DE slanting to the A gap.
Versus the block down and kick out schemes like power the defense is able to get two blitzers to the point of attack.
As the OT blocks down the Mike is blitzing the B gap area. With 2 blitzers off the edge; the Mike is able to spill and the Sam is able to contain.
Versus the pass the offense is likely running a slide scheme away from the blitz. If that is the situation the blitz creates a 2 (Mike & Sam) on 1 (RB).
Here is some video of the Dick Lebeau coached Pittsburgh Steelers running the concept. This video is courtesy of an excellent article about Coach Lebeau's Strong Scrape Fire Zone from Coach Hoover.