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100 years of US routes: 1926-2026
Endpoints of
This page is about the east segment of US 20 (not to be confused with the separate west segment of US 20).
1926-present
East: Boston, MA
West: Yellowstone, WY
Mileage: in 1989 AASHTO listed a figure of 2376 miles for US 20[e]... however, that included the mileage of US 20's associated business and alternate routes. According to the state subtotals on AASHTO's 1989 spreadsheet, the actual end-to-end total of mainline US 20[e] at the time was 2352 miles. That closely matches our own 2020 measurement, which yielded 2346.5 miles. Want historic mileages? Our handy reference book includes the mileages that were published in all 13 of AASHO/AASHTO's historic route logs (spanning the years 1927 to 1989).
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US 20 does not exist within Yellowstone National Park, and although the route is implied to run through Yellowstone, the Park divides US 20 into two separate segments.
The west end of US 20[e] has always been at the east entrance to Yellowstone National Park. This map showing the original extent of US 20 was included in a 1927 US Dept. of Agriculture Office of Information press release, issued shortly after the US routes were commissioned:
c. 1927, US Government Printing Office
Boston
The east terminus of US 20[e] has always been in Boston, although its exact endpoint has changed over the years. US 20 comes into town on Brighton Avenue, which then becomes Commonwealth Avenue. Formerly this was the last eastbound marker...
Elbert, Jul. 2006
...but in 2012 or 2013 it appears MassDoT re-signposted the routes in this part of town, and then the easternmost segment of US 20 had shields that were more MUTCD-compliant. As of 2014, the last eastbound marker was just past the BU Bridge:
Google Maps Street View, 2011 (gone by 2017)
Signage approaching Kenmore Square indicates the route at which US 20 terminates:
Google Maps Street View, 2014
Morrison, Oct. 2017
MA hwy. 2 approaches Commonwealth from the right, via Beacon Street. Here, where those two roads intersect, MA 2 switches over to Commonwealth, and the US 20 designation ends. For years there was a sign assembly attesting to that fact, but when that traffic island was altered in about 2008, this "End" sign was removed and not replaced until 2017:
Moraseski
Elbert, Jul. 2006
Bourey, Mar. 2017
Morrison, Oct. 2017
Originally the US 20 designation extended further ahead via Beacon and ended at the State House:
c. 1932, MassDOT
This shot was looking east on Beacon at Park Street. The State House is off the left side of the photo, so this was US 20's original terminus:
TopHatGuy, Apr. 2019
In 1938, part of Beacon became one-way westbound, so US 20 was moved from Beacon to Commonwealth Avenue, and its terminus was changed to the Public Garden:
c. 1956, Gousha
This photo was taken looking eastbound on Commonwealth. The cross road is Arlington Street; beyond that is the Public Garden, and in the background some of the skyscrapers in the city center are visible. So this is the perspective of a driver at US 20's second terminus in Boston:
TopHatGuy, Apr. 2019
TopHatGuy, Apr. 2019
That photo was looking the opposite direction (west on Commonwealth from the Public Garden). Today that is designated MA state route 2, but historically that was the east beginning of US 20. In 1963, US 1 traffic was redirected through Back Bay (instead of through MIT) along a routing that included Commonwealth. That may have been what prompted the truncation of US 20 to its current terminus. About a mile ahead, as one approaches the intersection with Beacon, signs note that the junction with US 20 is upcoming...
Google Maps Street View, 2014
...and in December 2016 a new sign was installed on westbound Commonwealth, just before the beginning of US 20...
MassDoT, Dec. 2016 (linked to source)
...but unfortunately the mileage on that sign is significantly overstated. MassDoT copied the information from a similar sign that was posted at the route's western terminus in Oregon.
On westbound Beacon, there is also a reference to US 20 just prior to its eastern beginning:
Google Maps Street View, 2014
Just ahead, where Commonwealth and Beacon traffic diverge, US 20 begins at Kenmore Square:
Google Maps Street View, 2014
Morrison, Oct. 2017
These photos show the first westbound markers, as they appeared in the past and more recently:
Mortell, 1999
Morrison, Oct. 2017
Research and/or image credits: George Bourey; Wayne Brunelle; Nancy Cooper; Chris Elbert; Dan Moraseski; Jeff Morrison; Robert Mortell; Dale Sanderson; Michael Summa; TopHatGuy; Joe Zelinski
Page originally created 2000;last updated May 4, 2025.
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