Mileage: US 6 vs. US 20

	A	B	C	D	E	F
1	US 6 states	Google Maps	DOT mileage	Difference	Source
2	Massachusetts	117.8	118.58	-0.78	See "MA" tab	https://gis.massdot.state.ma.us/mrla/
3	Rhode Island	26.5	26.532	-0.032	See "RI" tab
4	Connecticut	116.4	116.33	0.07	See "CT" tab	https://portal.ct.gov/DOT/IT/Other-Materials-and-Reports
5	New York	76.1	77.85	-1.75	See "NY" tab	https://www.dot.ny.gov/divisions/engineering/technical-services/highway-data-services/traffic-data
6	Pennsylvania	404.7	409	-4.3	See "PA" tab	DOT mileage not available; used 1989 AASHTO mileage (which probably slightly overstates the current mileage).
7	Ohio	247.4	248.185	-0.785	ODOT straight-line diagrams (by county)
8	Indiana	150.1	149.429	0.671	INDOT reference post book (2016)
9	Illinois	178.1	181	-2.9	--->	DOT mileage not available; used 1989 AASHTO mileage (which probably slightly overstates the current mileage).
10	Iowa	322	322.455	-0.455	See "IA" tab
11	Nebraska	372.2	373.28	-1.08	See "NE" tab	https://www.nebraskamap.gov/datasets/nebraska::highways/
12	Colorado	474.6	474	0.6	--->	DOT mileage not available; used 1989 AASHTO mileage.
13	Utah	373.8	373.753	0.047	See "UT" tab
14	Nevada	305.2	305.48	-0.28	See "NV" tab	https://www.dot.nv.gov/doing-business/about-ndot/ndot-divisions/planning/roadway-systems/state-maintained-highways-descriptions-index-maps
15	California	40.5	40.505	-0.005	CalTrans truck route list
16	Totals	3205.4	3216.379	10.979
17
18	US 20 states	Google Maps	DOT mileage	Difference
19	Massachusetts	153.1	154.07	-0.97	See "MA" tab	https://gis.massdot.state.ma.us/mrla/
20	New York	371.2	371.42	-0.22	See "NY" tab	https://www.dot.ny.gov/divisions/engineering/technical-services/highway-data-services/traffic-data
21	Pennsylvania	45.2	45.43	-0.23	See "PA" tab	https://www.penndot.pa.gov/ProjectAndPrograms/Planning/TrafficInformation/Pages/2021-Highway-Statistics.aspx
22	Ohio	260.3	260.604	-0.304	ODOT straight-line diagrams (by county)
23	Indiana	155.4	153.45	1.95	INDOT reference post book (2016)
24	Illinois	197.9	196	1.9	--->	DOT mileage not available; used 1989 AASHTO mileage.
25	Iowa	300.1	300.282	-0.182	See "IA" tab
26	Nebraska	430.5	428.55	1.95	See "NE" tab	https://www.nebraskamap.gov/datasets/nebraska::highways/
27	Wyoming	432.8	433.336	-0.536	See "WY" tab
28	Montana	9.7	9.319	0.381	See "MT" tab	https://www.mdt.mt.gov/other/webdata/external/planning/ALTIS/ALTIS_Road_Log.pdf
29	Idaho	402.2	405.045	-2.845	See "ID" tab...	...but note: from their log figure of 406.3, my entry subtracts 1.255 miles worth of what the log refers to as "milepost equations", which are points where the mileage jumps due to highway realignments. https://apps.itd.idaho.gov/apps/milepointlog/
30	Oregon	446.1	447.26	-1.16	(unfortunately I lost this email from ODOT)
31	Totals	3204.5	3204.766	0.266
32
33	Difference:	0.9	11.613	10.713
34
35	US 20[E]:	2346.5	2343.142
36	US 20[W]:	858	861.624
37	Total:	3204.5	3204.766
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100