Progress in the value of the best known tour for pla85900 is recorded in the following table, together with the research team and the method used to obtain the new record results.

Date Tour Length Research Team Method
07.06.1991 142,514,146 David S. Johnson Iterated Lin-Kernighan
29.03.1996 142,487,006 Concorde Tour Merging
23.09.1997 142,482,068 Concorde Tour Merging
14.10.1998 142,416,327 Keld Helsgaun LKH
22.10.1999 142,409,553 Concorde Tour Merging
18.06.2001 142,406,493 Keld Helsgaun LKH
27.06.2001 142,405,532 Keld Helsgaun LKH
31.08.2001 142,395,130 Concorde Tour Merging with LKH
14.12.2001 142,393,738 Keld Helsgaun LKH
15.09.2002 142,385,237 Hisao Tamaki Approximate Tour Merging
12.12.2002 142,383,704 Keld Helsgaun LKH
19.03.2003 142,383,467 Nguyen Dinh Hung Hybrid Genetic Algorithm
28.04.2003 142,383,189 Keld Helsgaun LKH
23.12.2003 142,383,011 Keld Helsgaun LKH
02.05.2004 142,382,641 Keld Helsgaun LKH