The law says window frames on Capitol Hill must be wooden, or something that looks very much like wood. If a front door has two parts and opens down the middle, it cannot be replaced by a single door that swings open from the side. If the house was built two stories tall, it must remain two stories tall — unless the addition can’t be seen from the street.

Humans don’t like change, so it’s not surprising that historic preservation laws have become quite popular. There are now more than 2,300 local historic districts across the United States, and I know many people who would like to have their own neighborhood frozen in time.

But historic preservation comes at a cost: It obstructs change for the better. And while that price is generally invisible, it is now on public display because of the city’s efforts to prevent Washington homeowners in historic neighborhoods from installing visible rooftop solar panels.

As you may have heard, Earth is getting hotter because we’re burning too much carbon, and one small way people can reduce their use of carbon is to tap the sun for electricity.

I haven’t taken a poll, but I’m prepared to wager most residents of Washington’s historic districts agree that climate change is caused by humans and that we really ought to do something about it. But the mandarins of historic preservation — and a good many of my neighbors — regard allowing people to install rooftop solar panels with the kind of horror they usually reserve for, say, anachronistic window frames. (The Capitol Hill Restoration Society helpfully advises homeowners: “In the Historic District you should not even consider using vinyl windows.” That’s right — please stop thinking about vinyl, immediately.)

“I applaud your greenness, and your desire to save the planet. And I realize that we are in crisis, politically as well as sustainably,” Chris Landis, an architect who sat on one of the boards that pass judgment on proposed changes to Washington homes, told a homeowner in October who had the temerity to request permission to install 12 front-facing solar panels on his own roof. “But I just have this vision of a row of houses with solar panels on the front of them and it just — it upsets me, as somebody who’s supposed to protect the architectural fabric of a neighborhood.” (The quote is from a Washington Post article, with plenty more like it.)

Mr. Landis and I apparently don’t share a sense of the sacrifices that may be required in a crisis. As the petitioner, Steven Preister, put the matter to Mr. Landis and his colleagues: “If we do not change and loosen these standards, will the district be habitable in 100 years?”

Good question!

The board, however, decided it was more important to keep Mr. Preister’s roof looking as it did 100 years ago.

Petition: Denied.

I am well aware that installing solar panels on every house in Washington — or even in the United States — would not suffice to make a significant dent in the pace of global warming.

And it should be noted that after Mr. Preister’s failure caused an uproar, the city announced changes that make it a little easier to win permission to put solar panels on historic homes. Mr. Preister finally won permission after promising to spend some $1,300 on camouflage.

But the fact that Washington continues to impose any aesthetic restrictions on rooftop solar panels is still a problem — and it is emblematic of the broader problems with preservation.

There are buildings that should be preserved because of their historic, cultural or aesthetic significance. But there aren’t many. The list certainly doesn’t include all 8,000 buildings in the Capitol Hill Historic District.

Historic preservation, in practice, is not about preserving history. It is about preserving the lifestyle of an affluent urban elite.

We are placing large chunks of our cities under glass, preventing what should be some of our most vibrant neighborhoods from growing and changing as the country grows and changes.

The Dutch architect Rem Koolhaas has shrewdly observed that “preservation is not the enemy of modernity but actually one of its inventions…. The whole idea of modernization raises, whether latently or overtly, the issue of what to keep.”

If people were interested in preserving history, he said, they should preserve everything: The pretty and ugly houses; grande olde theatres and strip malls. He suggested, tongue in cheek, that cities should be sliced into strips, with everything in one strip preserved and everything in the next open for development.

That’s not how we do it, of course.

Homes in Washington’s historic districts are modern on the inside. Cable lines run between houses, cars are parked on the streets, and the government has set aside the deed restrictions that in some neighborhoods once barred ownership by blacks, Jews and other minorities. What is being preserved are the facades of the houses — and the scale of development.

Those limits on renovation and construction are directly connected to the fact that people live in tents under the highway at the edge of my neighborhood. Our cities, as Mr. Koolhaas put it, have become “suffocatingly stable” in the center and “alarmingly unstable at the periphery.”

The necessary corrective is not to demolish existing buildings, but to allow most existing buildings to be changed over time, and to allow new buildings to grow up alongside.

American cities should borrow a page from Britain, where protected buildings are placed in categories, from most to least important. In my neighborhood, the Capitol is an obvious example of a building that deserves full protection. Perhaps the local Carnegie library belongs in an intermediate category. But houses, with rare exceptions, are not historically significant. Residential historic districts mostly serve to protect property values, and the government should stop privileging that goal over other values like access to affordable housing. Or the value of trying something new. Or, say, the value of doing something to slow global warming and preserve a habitable planet.

One of the important March for Life event and the first one is the President’s speech on anti-abortion demonstration on Friday in Washington.

Mr. Trump’s surprise announcement, made on Twitter on Wednesday as the Senate began hearing opening arguments in his impeachment trial, is his latest gesture of support for a cause dear to evangelical Christians who are a core part of his conservative base.

No president has personally attended the march in its 47-year history. Past Republican presidents might have been inclined to attend, but either on the advice of staff or their own instincts saw it as a step too far and instead showed their support in less visible ways, like through remote messages or by meeting with activists.

Mr. Trump, who once called himself “very pro-choice,” has until now addressed the group only remotely and welcomed some marchers at the White House.

But as he has battled for political survival in the face of multiple investigations and a re-election campaign, he has made increasingly warm overtures to evangelicals and sought to cast himself as the most firmly anti-abortion president in at least a generation.

His administration has already embraced the march, which draws thousands of attendees, in unprecedented ways. In 2017, Mike Pence became the first sitting vice president to attend the event, and the next year, Mr. Trump became the first president to address the rally by video. In his speech, the president vowed that his administration would “always defend the very first right in the Declaration of Independence, and that is the right to life.”

Many of the evangelical Christians who most strongly oppose abortion find Mr. Trump’s two divorces, penchant for profanity and lack of demonstrated interest in religion before he entered politics to be unsettling. But as a political bloc, they have stood by him loyally as he hands them long-sought judicial appointments and policy changes.

In a statement, Jeanne Mancini, the president of March for Life, praised the president for appointing anti-abortion judges, cutting taxpayer funding for abortions in the United States and abroad, and outspokenly opposing late-term abortions.

“President Trump and his administration have been consistent champions for life,” she said, “and their support for the March for Life has been unwavering.”

Mr. Trump’s announcement comes a few days after the Susan B. Anthony List, an anti-abortion political action group, announced that it would spend $52 million to support the president and other Republican candidates in the 2020 election cycle, a sum the group called a record.

The group’s president, Marjorie Dannenfelser, a former chairwoman of the 2016 Trump campaign’s Pro-Life Coalition, said in a statement that Mr. Trump’s attendance at the March for Life “signals a watershed moment for the pro-life movement.”

The March for Life, which has its headquarters in downtown Washington, says its mission is to “promote the beauty and dignity of every human life by working to end abortion — uniting, educating, and mobilizing pro-life people in the public square.”

On Twitter, Ilyse Hogue, the president of NARAL Pro-Choice America, called the president’s announcement “a desperate attempt to divert attention from his criminal presidency and fire up his radical base.”

Writing in the conservative news outlet The Daily Wire on Wednesday, Russell T. Vought, Mr. Trump’s acting director of the Office of Management and Budget, called him “the most pro-life president in history” and celebrated what he called “a golden chapter for our movement.”

US Census Bureau figures show that in 2018, UK exports to New York, California, Texas and Georgia were worth more than $5bn (£3.8bn) per state in 2018.

Paul Grossman, director of US trade at OCO Global, a Belfast-based trade and investment consultancy firm that works with DIT, said billions more dollars worth of trade with these states could be added through enhanced diplomacy targeted at the state level, for example to create opportunities for government procurement and remove non-tariff barriers.

In March, OCO Global is managing a trade mission of 10 states – including Mississippi, South Carolina, Georgia, Virginia, Maryland, Tennessee and Oregon – to London to meet officials from DIT.

“The states recognise that it’s a time in history when they can recoup the benefit of building strong relationships with the businesses that the UK Government helps to export,” Mr Grossman said. “If you want to get the work done – the doors opened and the deals closed – that’s done at the state level.”

The former trade secretary Liam Fox proposed last week that Boris Johnson should negotiate agreements with individual US states as a backstop while he tries to strike a post-Brexit free-trade agreement with America, which it is hoped would focus minds in Brussels to seal an EU-UK deal by the end of this year so that the Brexit transition period does not need to be extended.