Additional data gathered in May indicates that the government's first estimate of the U.S. gross domestic product was a pretty good one. Its first revision provided the same 1.8% annualized growth rate initially projected in April, according to the Bureau of Economic Analysis. So unlike most times when GDP is revised, there isn't much to explain about what changed. However, a few components within the calculation did shift, even though the headline number was not revised.
As a reminder, here's the chart:
Obviously, this looks identical to the chart from April, since GDP was not revised. If you want to get very technical, the growth rate was slightly different: in April it was rounded up to 1.8% from 1.75%, but the new revision revises it down to 1.8% from 1.83%. So growth was actually slightly better than we thought.
As for GDP's components, let's get the easy ones out of the way first: net exports and government spending both had virtually identical contributions to growth as was estimated in April. The dollar value of exports was a bit higher than we thought, but since imports were also proportionally higher the contribution of net exports did not change. From the fourth quarter, net exports remained flat. Government spending was pretty accurately estimated the first time around. It held growth back by shrinking at a seasonally adjusted, annualized rate of $35 billion.