"One red light town" meaning

You were correct, but if you had searched for slight variations (one/single, red light/traffic light/stoplight), you would have found it easily. The following list of words with similar meaning gives an idea of what it can mean if used figuratively.

one-horse town, backwater, backwoods, boondocks, bump in the road, hick town, jerkwater town, jumping-off place, middle of nowhere, one-blink town, one-gas-station town, tank town, the sticks, whistlestop, wide place in the road, Podunk, frontier, backlands backcountry, bush, up-country, hinterland, outlands, outback, the back of beyond, isolated place, sleepy town, back of beyond, remote place, sticks, the middle of nowhere, secluded spot

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