A new exhibit billed as a “once-in-a-generation” display of historic maps of Texas opens Friday at the Witte Museum, featuring as its showpiece a giant map drawn by Stephen F. Austin that is rarely seen by the public.

The fragile 1833-1837 map drawn by Austin, an empresario and renowned “Father of Texas,” and completed by other cartographers shows Austin’s East Texas colony and much of the state in a 7-by-7-foot custom-made case.

The exhibit, “Mapping Texas: From Frontier to the Lone Star State,” features more than 40 original maps, letters and early census documents from collections of the Witte, Texas General Land Office, and Frank and Carol Holcomb of Houston. It runs through Sept. 5.

In a time before computers and satellite imagery, when surveyors and mapmakers used a sighting compass and a measuring chain, working out of tents on the frontier for months at a time, Austin and others achieved amazing accuracy while mapping the “Old 300” colony and surrounding region, from San Antonio to Harrisburg — today’s Houston.

“We actually have geo-referenced this map at the Land Office, and it is remarkable how well the rivers and streams line up. Most everything is where it’s supposed to be,” said James Harkins, Land Office director of public services.

Officials announced a first-ever collaboration of the Witte and Land Office, the oldest state agency in Texas, at a news conference Thursday.

“These maps of what is now Texas are pieces of art,” said Marise McDermott, Witte president and CEO. “Every single one of these maps underscores that San Antonio is the center of the frontier.”

Museum officials said they began talking with the Land Office more than a year ago about bringing together a carefully selected group of rare, old maps, providing an opportunity many people have never had, to see how Texas evolved from the 1500s to 1800s.

“It is a historic exhibit. This is a one-time event,” said Bruce Shackleford, the Witte’s curator of South Texas heritage.

“What happened in this state affected the whole United States (and) Mexico, coast-to-coast. That’s extremely important. And these maps show that,” he said. “For me, these are some of the great treasures of the state of Texas.”

Harkins said it is the first time that three of Austin’s “most important maps will be on exhibit together, probably since they were in his office whenever he was working in his colony.”

“And it may be the last time they’re ever shown together,” because of their fragile condition, he said.

One map from 1818, drawn in Philadelphia by John Melish, shows what now is the United States during Spanish rule in Texas, with the possibility of westward expansion to California.

“It doesn’t really show you Texas, but we know where it is. It’s part of the Spanish empire. This is a really important map,” said José Adrián Barragán, Spanish translator at the Land Office.

Other maps were produced in New York and even Weisbaden, Germany — for Germans considering immigration to Texas in the 1800s. Occasionally, the mapmakers made mistakes.

“A lot of times, Texas was mapped from the outside, looking in,” Barragán said. “Sometimes they make horrible errors, where California becomes an island all of a sudden. That’s just the information they were receiving.”

shuddleston@express-news.net

Twitter: @shuddlestonSA