Different cities you have lived in that are connected by the same highway

[Mike_OH]

Cincinnati, OH and Portsmouth, OH (US 52)

[ChoralScholar]

Harrison, Greenbrier, Conway, and Pine Bluff, Arkansas - connected by US 65
Atkins, Russellville, and Conway, Arkansas - connected by US 64 (and I-40)

[JCinSummerfield]

Not that I've been a worldly person...US-23, Ypsilanti & Petersburg, MI

[hm insulators]

Los Angeles and Phoenix which are connected by I-10.

[JMoses24]

Hamilton, Ohio; Cincinnati, Ohio; and Florence, KY: US 127
Cincinnati and Florence are also linked via I-71/I-75, US 42 and US 25
Hamilton and Cincinnati are also linked via OH SR 4 (US 27 technically doesn't enter the city of Hamilton itself but passes through the village of Ross, which also uses a Hamilton ZIP code -- so you could count that)
Harrison, Ohio and Hamilton: OH SR 128

[bdmoss88]

Gordo, AL-Montgomery, AL, US82
Auburn, AL-Salisbury, NC, I85, US29
Haleyville, AL-Phil Campbell,AL, AL13

[doorknob60]

Not quite the same, but we took a camping trip to Yellowstone from Bend, and the campground we stayed at was on US-20 (right on it, near West Yellowstone, MT). As we left Bend two days earlier, yup, US-20. We didn't take 20 the whole way though, we used the interstates through Idaho, and took I-90 to US-395 to I-84 to US-97 on the way back. I don't think I've technically lived in two cities on the same highway, unless you count cities like Forest Grove, OR or Battle Ground, WA as being on I-5 (which they aren't). Or, if you count living in a hotel for 2 months in Eugene before moving permanently to Springfield (same situation in Pasco and West Richland), but those are neighboring cities, so that's boring.

EDIT: I thought of one. Yakima and Bend, both on US-97. I forgot, because I only lived in Yakima when I was very young. And while we're at it, Yakima and Pasco/West Richland are both on US-12 (and very near I-82).