Apparently it happened on Dec. 14, 2009, but his memorial service was only held at Columbia University on April 11, and I only just became aware of it through a posting by Peter Boettke. There are various links there, including to an obit in the Boston Globe. He was 97 years old, and not well known by the time of his death, although quite prominent in an earlier era. He was a specialist in public finance and land use, among many other topics, serving on the board of directors of the Lincoln Institute of Land Policy for many years, where he expressed sympathy with Georgist views and broader tax simplification, while declaring that he did not like the term "land value taxation."
He was not easy to classify. Nominally a Republican and a member of the Mont Pelerin Society, he nevertheless was a close friend of the late William Vickrey, whom he was with when I first met him at an Eastern Economic Association meeting back in the early 1990s. Vickrey was very much on a push for policies to guarantee full employment, and I heard Harriss agreeing with him on this. When Vickrey died three days after receiving the Nobel Prize in economics in 1996, it was Harriss who spoke in his place at the Nobel ceremony in Stockholm and forcefully presented his friend's arguments for vigorous policies to achieve full employment, something that would make both of them very relevant today.
From what I saw and what I have read elsewhere, Lowell Harriss was kind and wise and polite to all he met, a gentleman scholar of the old school, and one who will be missed.