These people like mathematical series...........the Fibonacci sequence in the Da vinci code............the harmonic series......for the Riemann hypothesis, etc.....

Also........u c all 3 primary colors.........evenly spaced out..........red...........a skip,,,,,,,,,blue........a skip.......then yellow.........................but red and blue do not make orange...........but blue and yellow do make green..................so there seem to be exceptions.................




Anyways.............what might be significant in that order..................well if u start Red then Orange..........that is the start of Roy g biv..........but green should come before blue............silver is last...........the South is in charge..........

A painter's palette..................the list in the DC metro poster is not in that same order as below.............they have it........Red, Orange, Blue, Green, Yellow, Silver..........................

Line Name	Opened	Stations	Distance		Termini
			mi	km	Western/Southern	Eastern/Northern
Red Line	1976	27	31.9	51.3	Shady Grove	Glenmont
Blue Line	1977	27	30.3	48.8	Franconia–Springfield	Largo Town Center
Orange Line	1978	26	26.4	42.5	Vienna	New Carrollton
Yellow Line	1983	17	15.07	24.25	Huntington Franconia–Springfield(Rush+)	Mount Vernon Square (rush hours) Greenbelt (Rush+) Fort Totten (other times)
Green Line	1991	21	23.04	37.08	Branch Avenue	Greenbelt
Silver Line	2014	28	29.6	47.6	Wiehle–Reston East Ashburn (opens 2019)	Largo Town Center