Sept 2 (Reuters) - Wall Street's main indexes opened

lower on Tuesday, as investors returning from a long holiday

weekend worried about the legality of U.S. President Donald

Trump's tariffs and awaited crucial economic reports.

The Dow Jones Industrial Average fell 257.1 points,

or 0.56%, at the open to 45,287.73. The S&P 500 fell 58.7

points, or 0.91%, to 6,401.51​, while the Nasdaq Composite

dropped 369.0 points, or 1.72%, to 21,086.575.