In my area (HCSO, PCPD) you could tell by their boots: jackboots = traffic enforcement.

Of course there's also FHP, who are basically an entire agency of only traffic enforcement.

I'd recommend getting a dash cam and your speedometer calibrated, just in case you got a wheel resize or gear configuration change that made your speedometer inaccurate. We were required to calibrate our patrol cars every year if we used it to measure speed, but there is zero such requirement for random motorists. I think the LIDAR and RADAR guns were yearly too, but I never applied for the class required to use one so I'm not sure.