Each time the summer solstice comes around it means the longest day of the year is upon us. In Alaska this is a day with almost 24 hours of daylight, depending on where you are located. Think of what you could do on the longest day of the year if you have almost 24 hours of sunlight? You could probably get moved to your new apartment and unpacked all in one day. Of course, if you intend on a long distance move it would definitely take longer, but the point is that on the first day of summer you could certainly benefit from the long daylight hours, whether you have packing to do for your move or need a few extra hours to drive to your next rest stop on the way to your new home.
The summer solstice is the day on which the sun reaches the farthest point north from the equator and can fall on the 20th or 21st June, depending on your time zone. The sun almost seems to stop on this day and appears much higher in the sky. The winter solstice is just as interesting, with the least amount of daylight hours for a long distance move of the whole year.
The holiday or solstice has meant different things throughout time, depending on religion and beliefs, which is another reason many people continue to mark their calendar over and above the fact that it is the first day of summer.