There's a blue pipe (1" diameter) extending ~3 feet from the city water meter before transitioning to 1" copper, then the copper connects 2 feet later to my rusted galvanized. I've run new pex-a pipe throughout the house, copper for above-ground section (e.g. hose bibs, shut-off valve), and planned to run pvc schedule 80 to the service line. Thought the service line was copper but turns out it's a blue pipe.
Every picture I've seen of polybutylene shows it as pale blue
PEX is almost always bright blue (when it is blue). In addition, polybutylene breaks down over time. The chances it's survived in a water main this long is low.