It was a desperately disappointing afternoon for Anderson, the world number 32 playing in his maiden Slam final at the 34th attempt.
He was the first South African in a US championship final since Cliff Drysdale in 1965 and was bidding to become his country’s first Slam champion since Johan Kriek at the 1981 Australian Open.
The Johannesburg-born, Florida-based Anderson finished the 2hr 28min final with 40 unforced errors to Nadal’s 11, failing even to carve out a single break point.
Nadal, winning his first hardcourt title since January 2014 in Doha, gave up just 15 points on his serve and won 16 out of 16 net points.
“Rafa, we are the same age but I have looked up to you all of my life,” said Anderson.
“It was an honour playing you. You are one of the great ambassadors of our sport.”
In a final guaranteed to result in the fifth Slam champion in succession who is 30 or older, Nadal was on top from the start.
He had 28th-seeded Anderson scrambling to save two break points in the third and fifth games before the Spaniard converted his fifth off a forehand error for a 4-3 lead.
The world No 1 held and broke again, cleverly forcing the 31-year-old South African out of position on set point after 58 minutes of action.
By the end of the opening set, Nadal had just five unforced errors to Anderson’s 23 with the South African unable to muster a single break point.
The one-way traffic continued in the second set as Nadal broke for 4-2 off the back of three successive volleys.
Anderson even collected a time violation for his troubles as his efforts to compose himself failed horribly.
A brutal crosscourt forehand winner gave Nadal the second set 6-3.
Anderson was broken again in the opening game of the third set.
It was his fourth loss of serve in the final; before Sunday, he had been broken just five times in the entire tournament.
Anderson called the trainer for a bloodied right index finger after the fifth game, but his struggles continued.
He saved a match point but Nadal wrapped it up with a clinical backhand volley.