I live a few blocks from there, at Day and Orchard streets. If you look carefully at the permit parkng signs in our neighborhood, you’ll see that Somerville and Cambridge signs look somewhat different. The section of Russell Street that this person parked on is in Somerville, despite the fact that the houses on the east side of it are in Cambridge. The city line actually runs through the front yards.

Tip O'Neill lived in one of these houses, and he had to pay a small amount of his property tax to Somerville.

People who live on Russell Street can get residential permits from both cities, but one of them will say "Russell Street only". There's a similar arrangement for Line Street, where the city line runs down the middle of the street, but parking is allowed on only one side.