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Flight instructor here. That is called a beacon, and airports still have them. And none of them have ever been blue. It may appear blue from the ground but the beam is actually green. The colors actually encode what kind of airport they're at.
At a normal civilian airport that has runways, the beacon will be green and white.
At a military airfield, the beam will flash green and then two whites.
At a heliport with only helipads for helicopters, the beacon will be green, yellow, white.
At a seaplane base, the beacon will be white and yellow.
The beacon will operate from sunset to sunrise, and also during daylight when instrument conditions prevail.
Bonus airport light fact: some smaller, less busy airports like your typical county airport probably does not turn all of its surface lights on all of the time. It'll run the beacon to help pilots find the airport, but the runway and taxiway lights will remain off. Pilots are able to turn them on from the air by tuning their radios to the airport's UNICOM frequency and pushing the PTT key several times in rapid succession. Quite often the brightness is controllable whether you press the key 5, 7 or 9 times. This is called Pilot Controlled Lighting. It's an energy saving system that's been around for decades now, and a fun magic trick for private pilots to pull on their friends lucky enough to be invited on a night flight.
I've witnessed the lights getting turned on for a landing when driving past my local airport before. That's neat to know it might be pilot controlled!
It's possible to look that up in a document called the Airport Facility Directory (which they now call Chart Supplements apparently) but if you don't speak pilotese you're not going to make heads or tails of it. Here's the line that instructs pilots that there's pilot controlled lighting at the first airport I ever landed at:
That expands to "Activate Medium Intensity Approach Light System for runway 5, Runway End Identifier Lights for runway 23, Precision Approach Path Indicator for runway 5 and 23, High Intensity Runway Lights on runway 5 and 23 on the Common Traffic Advisory Frequency." It's actually weird to me the PAPI is pilot controlled; usually those are constantly on because they're useful even during the day.