The oil pipeline project is bad for the United States for a variety of reasons. It destroys artifacts, pollutes the environment, and goes through preserved Native American land. These pipelines get protested every time they are proposed because they do so much irreversible damage to the land and the people on it.
Many may be callously dismissive of the sacred value of Native American sites, but they are fools if they ignore the threat that the continued consumption of fossil fuels represents to them, their children, and the biosphere entire. I wish the best of luck to the Standing Rock Sioux. They are fighting not just for themselves, but for all living things on earth.
Current pipelines do not harm any land or animals around them and the land they are on can be traveled on by foot without any difficulty. The pipeline would also be a boost to the economy. I have pipelines near me and I have never heard of any problems that they have caused.
In times where the GDP is suffering, our focus needs to be on the future, not the past. There are many sites where archeologists can excavate artificats, not simply those sites where pipeline construction remains. It is important for both sides to come to a mutual understanding of each other's desires and work together, not against each other.
The U.S still imports more oil than it produces to meet the demand within the country. This foreign detracts from the economy through import tax and also makes the country dependent on other countries. This pipeline will increase domestic output and energy independence. It has secondary benefits through the investment into its production that will produce thousands of jobs and boosts to local revenues, along with the increased tax revenues that can be spent on local services.