how wide is the grand canyon at its widest point?

The Grand canyon is 18 miles wide at its widest point.

How long is the Colorado river, which flows through the grand canyon?

the Colorado River is 1,450 miles long.

What is the area of grand canyon 

national park?

the national park is 1,902 square miles.

What year did the grand canyon become a national park?

it became a national park in 1919.

How many people visit the grand canyon each year?

over 5,000,000 people visit the grand canyon every year.

How old is the vishnu schist (the oldest rock formation in the grand canyon)?

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it is estimated to be 1.7 to 1.8 billion years old.

how deep is the grand canyon at its deepest point?

it is approximately 6,000 feet deep, over one mile.