What is the meaning of Cathy Song's "Heaven"?

Cathy Song, an Asian poet, elegantly describes a scene between the narrator and her son in the poem, "Heaven." Her son who is part caucasian thinks that when he dies he will go to a Chinese heaven; and except for his blond hair,  everyone will look like him.  As they look at the map, the boy's hand spreads out  to show the distance from his home to China. 

Their home, probably in Colorado, shows up only as a black dot. The poet thinks that their home is much like the wild west of the past when her grandfather worked on the railroad never thinking that this would become the place  where he would die.   She even wonders if there is a boy in China much like her son who dreams of coming to America.  Like her ancestor, she asks why am I here and why this place.

For two generations, none of her family has thought to go back to his homeland.  As she and her children stand in their backyard, they can see the mountains and the blue sky.  Her son,  who dreams of going to China, imagines the laundry on the clothesline as his ship with sails blowing in the breeze taking him all the way to heaven.