Idon't understand this poem, and i read it about 5 times.
making a fist for the first time, on the road north of tampico i felt the life sliding out of me a drum in the desert, harder and harder to hear i was seven, i lay in the car watching palm trees swirl a sickening pattern past the glass my stomach was a melon split wide inside my skin how do you know if you are going to die? " i begged my mother we had been traveling for days with strange confidence she answered "when you can no longer make a fist." years later i smile to think of that journey the borders we must cross separatley, stamped with our umaswerable woes i who did not die, who am still living, still lying in the backseat behind all my questions
clenching and opening one small hand.

I get you this poem is confusing and hard to understand. You have to read it several times to truly understand it. Ok but next time you don't understand a poem that has a complicated language copy the text and go to rewordify.com. Paste it. It will translate all those complicated words to simple words. Try it. 
 
Nye describes her experience being comforted by her mother when she was sick. Her mother told her she was not dying as long as she still had the strength to make a fist. Nye then writes that she is still comforted by this thought.

The poem has several devices such as:

Allusion it can be applied because it refers to a past historical event.
Imagery because it describes in detail the palm trees. Among other things. 

The tone is nostalgic because she is looking back on she was traveling but she also uses a tone of pride because she survived the journey and she can still make her hand into a fist .

Firstly, I think you may have written a word wrong "umaswerable", and I'd like to know what word actually should be there? Secondly, I'm not that familiar with that part of the world (Mexico), but from the poem I would say they were on the run (trying to flee their country) or just were living in the car, because they didn't have enough money. Both could be true, the first one at the beginning and the second one after. The boy clearly suffered some sort of trauma (at age 7) and may even have lost a hand ("one small hand") and they have had a rough time since ("umasw... woes").

During his experiment in Walden Pond, Thoreau reflected on the connection between travel, technology and economy. Thoreau believes that the best way to live life is to have a simple life with few worries. He argues that, in order for people to acquire luxury, they need to work an excessive amount of time. In order to free ourselves, we need to live a "simple" life.

The idea of a "simple" life requires us to give up some aspects of our lives that are not necessary. For example, modern travel. Thoreau argues that railroad travel is a modern invention that is not necessary, and that it has taken us farther away from a more desirable simple life. He also argues that this is the case with technology. While some technology might indeed make our lives easier, for the most part this simply takes us away from a more satisfying, simple life. He says that "our inventions are wont to be pretty toys, which distract our attention from serious things."