Few people know Janesville or Rock County better than former Wisconsin State Sen. Tim Cullen, who proves the point again with his new book. It’s called “Disassembled,” and Cullen’s subtitle is a mouthful and a solid indicator of what readers can expect: “A native son on Janesville and General Motors, a story of grit, race, gender and wishful thinking and what it means for America.”

That’s a tall order of analysis and storytelling, which Cullen tackles with gusto in a couple hundred fascinating pages.

The former senator will be in Beloit on Wednesday for a 6:30 p.m. talk and book signing at the public library in the Eclipse Center. A book costs 20 bucks but Cullen is donating profits to diversity scholarships in Beloit and Janesville, so it’s for a good cause. Cullen made some money in the private sector between his stints in public service, and he has found several ways to give back in philanthropic endeavors.

“Disassembled” tells both the familiar and unfamiliar stories of what the massive General Motors plant meant to Janesville, and of the ultimately unsuccessful efforts to keep the factory operating when GM announced the plan to close it. Cullen was tapped to co-chair (with UAW Local 95 President Brad Dutcher) the long-shot effort to persuade GM to keep the plant open.

Cullen was raised in Janesville, part of an Irish Catholic union family, which surely explains his roots and ties to the Democratic Party. He paid his way through college working summers at GM, so the big factory held a special place in his heart.

For the better part of a century the GM plant was synonymous with Janesville, providing good jobs with good pay and benefits to thousands of people across the region. Because of Americans’ love of the automobile most folks surely believed the good times could never end.

But end they did, and Cullen cites such factors as technological change, globalization and high gas prices in bringing on GM’s problems. Cheap overseas labor undermined union bargaining power as corporate profits plummeted.

Change often was slow and painful, and it hadn’t always been about global economic conditions. Cullen writes powerfully about gender and race issues, and how tough it was for women and people of color to break into the ranks at GM, especially in higher-paying assignments. In that sense, GM was no different than most companies. Despite the soaring rhetoric of America’s founding, equality of opportunity always has been a hard-earned commodity.

In retrospect, it’s likely the Janesville GM plant had been doomed for decades. It was old. It was too expensive in the age of globalization. GM’s business plan was unsustainable and by 2008 the legendary company was in financial free-fall.

The effort by local and state officials to propose a plan to pitch to GM was admirable, and had support from all the key stakeholders. Nevertheless, the deck was stacked against it.

The former senator knows the details and writes with clarity, both about what made GM great and what led to its downfall in Janesville. Despite how familiar it all may sound to longtime Rock County residents, there’s a lot of new information here and it’s well worth the read.

For Beloiters, there are some real similarities between what GM meant to Janesville and what Beloit Corporation meant to Beloit. When both faded into oblivion in the same decade the two cities had to find ways to reinvent themselves. Beloit and Janesville are still working, with considerable success, to do so. Cullen is proud of that, as we all should be.

William Barth is the Editor of the Beloit Daily News.