Notable elevation change when running out of Hopkinton to Copley Square with a bunch of friends on Partiots Day:
Location, change & distance [gain/loss] avg grade% (note)
Mile 0.0, Downhill .6 [-143] -4.5%
Mile .6, Uphill .14 [+36] 4.9%
Mile .7, Downhill 3.0 [-187] -1.2% (very long section)
Mile 7.6, Uphill .13 [+31] 4.5%
Mile 7.8, Downhill .18 [-30] -3.2%
Mile 15.3, Downhill .6 [-118] -3.7%
Mile 16, Uphill .6 [+75] 2.4%
Mile 17.6, Uphill .3 [+74] 4.7%
Mile 19.2, Uphill .4 [+63] 3.0%
Mile 20.3, Uphill .4 [+97] 4.6% (Heartbreak)
Mile 21.0, Downhill .5 [-87] -3.3%
Mile 22.0, Downhill .5 [-57] -2.2%
Mile 23.1, Downhill 1.0 [-95] -1.8%
As suggested above, it's the downhill sections that can get one in trouble.