We were eating frozen custard, Mrs. McIlheran and I, and all around us people were incongruously happy.

I suppose they had their superficial reasons: We were in a pleasant garden outside the custard stand, the night was warm yet not sultry, a fountain splashed, children played, the flavor of the day had almonds. June’s endless rain was over, the Brewers were on a tear, and summer in my hometown, Milwaukee, is one long string of festivals.

Still, didn’t us fools understand? This is not the year for happiness, nor even contentment. These are hard times, an almost-recession, the coming-to-roost of all of the fell birds set in motion by eight years of President Bush. Custard should bring us no joy. Didn’t we know we hungered for change, not vanilla?

Nah. It’s party time. Earlier in the day on Saturday, some 10,000 or so people showed up to party at a factory in South Milwaukee, with beer tents, grills, and bands on a stage. The occasion was an open house at Bucyrus International. One of the two companies that dominate the market for giant mining shovels, Bucyrus wanted to show off its $200 million expansion — and maybe hire some people.

“We were taking applications,” a spokesman, Kent Henschen, said. Indeed, signs led you right to the table. Want to weld? “We still need people,” he said.

Mainly, though, the company was boasting. Thousands strolled through Bucyrus’s cathedral-sized shops, awed by gears 16 feet in diameter, with teeth that could encompass your wrist.

This was as hard-metal, hard-hat, and old-line as manufacturing gets, and except for this particular day, the plant works as fast as it can, making draglines and electric shovels the size of apartment buildings. The machines weigh as much as 16.8 million pounds and sell for as much as $150 million. Since 2005, as mining has boomed, the company had doubled its employment. It expects years of strong growth: With crude more than $100 a barrel, there’s a lot of Alberta oil sand to be dug.

Nor is Bucyrus alone. Eighty miles north, the Manitowoc Co. has $3.3 billion in backlogged orders for its cranes, sales of which are booming overseas. Across the supposed Rust Belt, one finds factories thriving by making things for other countries. American exports overall are up about 40% from the start of the last expansion and should hit $1.1 trillion this year. And while manufacturing payrolls have fallen overall, industrial output has been rising strongly. This combination signals higher productivity and better economic prospects for workers with in-demand skills.

Times may be tough in housing and finance, but the gloom is far from universal. Parts of the economy — manufacturing and agriculture, for instance — are doing well. This is worth remembering.

One otherwise gets the impression that things are rotten all over. We’re being told this for political purposes. We’re hearing the phrase “worst since the Great Depression” specifically so we grow depressed enough to permit the kind of tomfoolery that empowers Washington but can seize up what’s working.

Trade, for instance. Senator Obama has been backpedaling on his primary season talk of tearing up the North American Free Trade Agreement, but antipathy to free trade permeates the Democrat constituencies he needs to turn out in November. At the least, to win industrial swing states, Mr. Obama’s talking of conditioning and restricting trade, and one can see why: A June poll by CNN found that more than half of Americans now see foreign trade as a threat to the economy.

It isn’t a threat in South Milwaukee: Nearly 80% of Bucyrus’s output is exported. “Free trade is absolutely critical,” the chief executive office of Bucyrus, Tim Sullivan, told Senator McCain when the presumptive Republican nominee, a down-the-line free-trader, visited. The flood of imported goods that supposedly threatens us is made in factories built of metal mined with Bucyrus equipment and powered by coal dug with Bucyrus shovels.

Nor is trade a threat in New York. Mayor Bloomberg last week helped launch a seven-week bus tour by consumer electronics companies worried that protectionism would short out their industry. New York companies export $1.6 billion in electronics, an industry spokesman said. All this is at risk when half the country is convinced trade hurts and a presidential candidate seeks to mine such sentiment.

Beyond trade, Mr. Obama is betting on voters wanting change, hazily defined, and his party is selling itself as the emetic a sickened economy needs. The more pervasive the illness, the more power voters will cede a new administration to institute its prescriptions: more regulation, taxation, and federal control. For Democrats, it won’t do to stint on gloom, even when the economy stubbornly grows instead of shrinking.

Surely that’s a mere technicality. So we’re told we feel awful even as a metal-bending company celebrates change that’s already happening. Bucyrus machines its gears in an 1893 building, but it assembles its cranes in a shop put up last year. Not knowing they were supposed to be miserable, employees cheerily explained to visitors how their work added up to an awesome mass of metal and prosperity, the latter sadly invisible to too many Americans.

Bucyrus will open a company museum next year, Mr. Henschen says, but there won’t be another open house for a few years. The company can’t afford to lose a day of production annually, he says, not when business is booming.

Mr. McIlheran is a contributing editor of The New York Sun.