The conventional progressive wisdom is that the Trump Administration will be bad for cities and for transit users. But in recent decades, a unified Republican government has been better for public transit than a divided government.
An efficient and equitable transport system must be diverse to serve diverse travel demands. Planners need better tools to quantify and communicate the benefits of walking, cycling and public transit to sometimes skeptical decision makers.
If you guessed cheap gas, love of automobiles, or preference for air travel, you are correct, but those fall under one reason, "lack of demand." Two additional reasons are offered in this article for the construction industry.