One of Washington's permanent parlor games is how much credit or blame a president deserves for the state of the economy. Inevitably, then, the question being asked now is whether Donald Trump or Barack Obama created today's strong economy. The correct answer is: neither. To the extent that personal responsibility can be assigned, the worthy recipient is Janet Yellen.
In practice, presidents' influence over the economy is limited. If it were otherwise, we'd live in an economic paradise. Unemployment would always be low, wages would always rise, and recessions would never occur. No one has that kind of power. Presidents and their agencies can't govern the business cycle.
The obvious qualification to this reality is the Federal Reserve. By regulating the flow of money and credit, the Fed stimulates or retards the economy, though not always in predictable ways. There are regular collisions between what the Fed can actually achieve and what the public thinks it should achieve. Yellen has led it since 2014 but will leave early next year and be replaced by Fed Gov. Jerome Powell.