From the crumbling bridges of California to the overflowing sewage drains of Houston and the rusting railroad tracks in the Northeast Corridor, decaying infrastructure is all around us, and the consequences are so familiar that we barely notice them—like urban traffic congestion, slow-moving trains, and flights that are often disrupted, thanks to an outdated air-traffic-control system. The costs are significant, once you reckon wasted time, lost productivity, poor public-health outcomes, and increased carbon emissions.

The economist Larry Summers has pointed out that, once you adjust for depreciation, the U.S. makes no annual net investment in public infrastructure at all. Yet polls show that infrastructure spending is popular with a majority of voters across the income spectrum. Historically, it enjoyed bipartisan support from politicians, too. If it’s so popular, why doesn’t it happen?

One clear reason is politics. While both parties remain rhetorically committed to infrastructure spending, in practice Republicans have been less willing to support it, especially when it goes toward things like public transit. This is partly because of the nature of the Republican base: public transit is hardly a priority for suburban and rural voters in the South and in much of the West. But ideology has played a key role as well. “The rise of modern conservatism, with its sense that government is the problem and its aversion to government spending, has created a Republican Party that’s much more skeptical of big infrastructure projects than it was.  Then the process of getting infrastructure projects approved has become riddled with what political scientists call “veto points.” There are more environmental regulations and more requirements for community input. There are often multiple governing bodies for new projects, each of which has to give its approval. Many of these veto points were put in place for good reason. But they make it harder to undertake big projects.  Mind you, this applies to most other countries as well, which doesn’t stop them getting things done.

Worse than the lack of new investment is our failure to maintain existing infrastructure. You have to spend more on maintenance as infrastructure ages, but we’ve been spending slightly less than we once did. The results are easy to see. In 2013, the Federal Transit Administration estimated that there’s an eighty-six-billion-dollar backlog in deferred maintenance on the nation’s rail and bus lines. The American Society of Civil Engineers, which gives America’s over-all infrastructure a grade of D-plus, has said that we would need to spend $3.6 trillion by 2020 to bring it up to snuff.

Maintenance is handled mainly by state and local communities, which, because many of them can’t run fiscal deficits, operate under budgetary pressures. Term limits mean that a politician who cuts maintenance spending may not be around when things go wrong. What politician doesn’t like opening something new and having a nice press op at the ribbon-cutting? But no one ever writes articles saying, “Region’s highways are still about as good as they were last year.”

The U.S. needs  a long-term strategy, fund it adequately, and hold the government accountable for making that strategy work. Infrastructure is the ultimate public good. Trump is right to make it a priority, but I reckon any attempt to put an infrastructure plan into action will go the way of the healthcare bill that failed yesterday.