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He needs to beat Ferrari's Sebastian Vettel by nine points and his Mercedes team-mate Nico Rosberg by two in the US on 25 October to seal a third title.
The Briton said: "I've never felt it's ever been done and dusted. There are still a lot of points available.
"I'm going to take my time and, at the next race, work as hard as ever."
Hamilton dominated in Russia following Rosberg's retirement early on with a throttle problem, the German having converted pole position into a lead on the first lap.
"The goal is to win a third title," Hamilton added. "Until I achieve that there is no other goal. I feel incredibly fortunate to have this car.
"I love going to Austin and the track has been amazing for me since the first race. I am looking forward to it, it is a track you can race on and get close to people."
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Rosberg's retirement meant he slipped back to third place in the championship, seven points behind Vettel. But he refused to concede his chances were over.
"I don't know," Rosberg said. "It has made it more difficult, of course. But I am never going to win it anyway with such normal things like that [the throttle] breaking.
"But of course I will keep pushing and keep attacking."
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Mercedes non-executive chairman Niki Lauda said: "He is very disappointed but he is a racing driver and he knows these things can happen.
"He led the race and could have won but these things happen. A racing driver never gives up, and especially Nico."
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Lewis Hamilton says there is "still a long way to go" in the Formula 1 title race despite moving to the brink of triumph with victory in Russia.