Local residents of a certain age can catalogue a host of changes they’ve witnessed in Northampton County over the years.

Veteran Lehigh Valley journalist and professor Glenn Kranzley has covered all the bases in his new book, “Still Changing, Still Home: Northampton County Since the 1950s.” He catches it all: from shrinking farmland to the traffic crunch, the economy, environment, culture, sports - you name it.

Kranzley presents a lecture, “Northampton County After Earth Day,” 2 p.m. April 21, Sigal Museum, 342 Northampton St., Easton.

The Sigal Museum is owned and operated by the Northampton County Historical and Genealogical Society, which commissioned Kranzley to write the book. After the lecture, copies of the book are expected to be available for purchase and signing by Kranzley.

Kranzley, a native of Allentown who has lived in Hellertown for many years, attended Allentown schools and received a degree in journalism from The Pennsylvania State University. He began his professional journalism career with the former Bethlehem Globe-Times in 1970 and later went on to The Morning Call, where he was editor of the opinion pages, retiring in 2009.

“I knew who the players were from my time at the newspapers,” Kranzley says. “Thanks to these people who were willing to talk to me, the book has some of the flavor, some personal stories. The bittersweet side of it is that six or seven of the folks have died and never got to see the finished product.”

The Kranzley book is intended as a followup to E. Gordon Alderfer’s 1953 book, “Northampton Heritage: The Story of an American County,” a history of Northampton County published by the Northampton County Historical and Genealogical Society to mark the 220th anniversary of the county. Kranzley’s book serves as the official update.

Kranzley worked with a fact-checking team, including Linda Heindel, volunteer chairperson, and a committee of advisors from the four Northampton County colleges and universities: Lehigh University, Lafayette University, Moravian College and Northampton Community College. “Chapter by chapter, I had to get it approved by the committee,” says Kranzley. “We started in 2011.”

Talking of the important changes in Northampton County, Kranzley emphasizes, “The economy is at the top of the list. Manufacturing has shrunk. However, we still have some iconic products from Northampton County: Martin Guitar, Peeps, Dixie Cups, Crayola crayons, and Orasure test strips.”

Still, the economy in the county has shifted drastically from the days when Bethlehem Steel Corp. was king. Today, the biggest employers are Lehigh Valley Health Network, St. Luke’s University Health Network, and Sands Casino Resort Bethlehem (built on the nation’s largest brownfield site, Bethlehem Steel’s former southside plant).

Kranzley cites the “real pride older steel workers and cement workers have in what they accomplished.”

The change in the demographics of the Northampton County population is another key theme Kranzley mentions, noting the move from predominately German, European, and British Isles heritage to a much more diverse population.

During the tumultuous mid- to late-1960s and early 1970s, the county managed with less violence than elsewhere.

“It was far more keeping the peace, not really tolerance. In 1970, at the South Bethlehem Protection Fire House, a youth center, some guys came by and fired several gunshots. A 14-year-old girl, Rose Marie Parham, was killed.

“Police responded with a get-tough policy. Later, there was a fight at the Old Ale House [at the Five Points, Broadway and Wyandotte streets]. Police herded everybody into police vans, including a local social worker [Robert Thompson]. A young patrolman handed in his gun and badge to Mayor Payrow on the spot.

“Globe-Times editor John Strohmeyer got involved and wound up winning a Pulitzer Prize for his editorials that helped calm Bethlehem.”

On the subject of his Sigal Museum lecture, Kranzley says, “The air and water are much cleaner. A lot is due to industries leaving, but the cement industries especially have taken steps to clean up. Attitudes slowly changed.” He cites the building of I-78 and the local protests that led to requiring a study of the affected environment before the interstate could be built.

Kranzley lauds Bethlehem Mayor Gordon Mowrer as the leader behind the beautification of Main Street in Bethlehem: “He recognized that Bethlehem had something to offer that no other city could. He got local and state dollars and identified things to bring people back to the city.”