“We are a nation of college-builders,” said John Thelin, a professor at the University of Kentucky. Every new community wants the benefits and prestige of a college, he said. “It’s comparable to landing an NFL franchise; I recall the joy in Washington, D.C. when you got your major-league baseball team: It made you complete.”

Thelin didn’t have anything to do with this map — it was designed by a guy working for a Web site, not an academic – but it does give a vivid broad-brush look at the trend lines over time that historians have studied.

Mike Simmons put it together. He works for the eCollegeFinder Web site, which offers information to students seeking information about colleges and generates revenue by selling that information to colleges trying to recruit them. Simmons  took a list of four-year colleges from the U.S. Department of Education and whittled it down by eliminating online-only schools and those for which he couldn’t quickly find a founding date.

So, don’t base your dissertation on this map. But Thelin — who has so much expertise in this that he not only wrote a book, “A History of American Higher Education (Johns Hopkins University Press), but even, with a summer job in construction, helped build the University of California at Irvine — said the number of colleges is always a little fluid, since they close, merge, adapt.

And the dots evoke the sweep of change in the new country, starting in 1636 with Harvard College and spreading slowly from colony to colony because it was difficult to get a charter. Then with the new nation, a groundswell began, as governors began using charters to pay off political debts, and settlers moved south and west across the country.

Religious schools were founded hither and thither and, in the late 19th and early 20th centuries, state universities spread. Colleges for blacks followed in segregated states, and universities followed population growth into cities.

Some changes happened quickly: In 1980, the Department of Education wasn’t counting for-profit four-year colleges, said Terry Hartle of the American Council on Education. By 2012 there were 782 of them. Another thing that keeps growing: The number of students enrolled in higher education, now something like 20 million, he said.