“I will be a president for all Americans,” said then President-elect Donald J. Trump in his victory speech in the early morning of Nov. 9, 2016.

Fast forward to the completion of Year One of the Trump presidency — Mr. Trump’s approval rating is the lowest in history for any first-year president, according to a Washington Post-ABC News poll.

Only 37 percent of Americans approve of Mr. Trump’s job performance. Many have expressed doubt in the president’s ability to fulfill the numerous and controversial promises he made as a candidate.

So what, exactly, has Mr. Trump accomplished to this point?

If Americans listen to him tell it, quite a bit (although the claims don’t always align with the facts).

Mr. Trump, a habitual user of Twitter, has declared his “successes” quite proudly through countless tweets. For example, Mr. Trump tweeted on Nov. 3: “JOBS, JOBS, JOBS!” with a picture attached that displays 261,000 jobs created in the month of October alone according to the Bureau of Labor Statistics. The following day, he tweeted: “Unemployment is down to 4.1%, lowest in 17 years. 1.5 million new jobs created since I took office. Highest stock Market ever, up $5.4 trill.”

Spoiler alert: Mr. Trump didn’t really do it.  

Most credit goes to former President Barack Obama, whose policies led to the numbers. Mr. Trump didn’t have enough time in office to significantly affect things to that point. Additionally, many of the numbers weren’t appreciably different than during Mr. Obama’s tenure.

According to the Bureau of Labor Statistics, the unemployment rate is indeed around 4 percent, but it’s part of a larger trend that started under Mr. Obama’s watch. In other words, this “accomplishment” can largely be credited to Mr. Obama’s policies, not Mr. Trump’s.

One could argue that Mr. Trump’s presence has had influence on the stock market, however. The Dow Jones Industrial Average is indeed at record heights. It has been rising steadily over the past year. Overall anticipation of regulatory cutbacks and tax breaks for businesses have played big factors.

Mr. Trump promised such results. But he also made other promises that have since been broken or haven’t panned out.

As a candidate, he promised to leave alone the Paris Climate Agreement. Then he said the United States would back out.

Mr. Trump has repeatedly said that he would build a wall along the Mexican border and that Mexico would pay for it. Last week, he asked Congress for $18 billion to build the wall, all the while insisting that Mexico would — eventually, somehow — still pay for it.

He promised the first thing he would do would be to repeal and replace the Affordable Care Act, or “Obamacare.” Despite controlling both houses of Congress, the Republicans struggled to agree on a plan and a haphazard bill (that more than 75 percent of Americans opposed) failed a crucial vote in the Senate.

Mr. Trump called for and promised a “total and complete shutdown of Muslims entering the United States.” His attempts to direct policy through executive orders failed as federal judges ruled against his measures.

He did, however, approve controversial plans on the Keystone Pipeline and a withdrawal from the Trans-Pacific Partnership trade agreement.

The Senate approved his appointment of Neil Gorsuch to the U.S. Supreme Court.

His only real legislative triumph, however, was getting an historic tax bill approved, lowering rates on the nation’s highest earners and big business — another plan that the vast majority of Americans opposed.

Mr. Trump’s approval rating continues to languish under 40 percent. His administration has been rocked by the release of a book detailing the first year of his presidency. Special prosecutor Robert Mueller continues to investigate potential ties to Russia during the election.

Mr. Trump arguably is a president to fewer than half of Americans. If he is serious about re-election, that number will have to shift significantly. And if Republicans lose any of their congressional power in this year’s midterm elections, that will be very difficult to do.