When the National Gallery of Art in Washington, D.C., launched Across the Nation last spring, it wasn’t clear how long the initiative to lend artworks from its collection to regional American museums would last. At the time, the NGA—with financial support from billionaire art collector and museum trustee Mitchell Rales —committed to lend up to ten artworks to ten partner institutions in in Alaska, Colorado, Connecticut, Idaho, Iowa, Michigan, Nevada, North Carolina, Utah, and Washington, covering expenses related to travel, installation, insurance, and marketing. Related Articles Now, Rales has stepped up with an additional $116 million donation to endow Across the Nation in perpetuity. (Rales and his brother, Steven Rales, founded the science and technology company Danaher Corporation in 1984.) Rales has been collecting contemporary art since the 1980s, much of which makes up the collection at Glenstone, a private museum in Potomac, Maryland, that Rales founded with his then-wife, Emily Wei Rales, in 2006.…