The Americans advanced by beating Mexico 2-0 while Costa Rica booked their spot after drawing 1-1 with Jamaica yesterday.
The qualifications were confirmed after Panama drew 2-2 with Honduras later Tuesday.
Goals from Eddie Johnson and Donovan fired the Americans to victory over their fierce regional rivals.
"It is pretty special," said Donovan. "I am proud of this team and proud of the hard work. Everyone deserves it so much."
It is the seventh straight World Cup finals appearance for the United States stretching back to 1990.
More From This Section
Honduras is third with 11 points while Panama sits fourth ahead of Mexico based on their better goals scored differential. They both have eight points while Jamaica is sixth with four points.
Johnson broke the deadlock in the 49th minute with a header before Donovan doubled the lead in the 78th from close range in front of a crowd of 24,584 at Columbus Crew Stadium.
"It was a tense game and a lot was at stake but everybody was so hungry for this win," said American coach Jurgen Klinsmann.
"In the second half we were fantastic," Howard said. "We knew we were going to create chances and we did.