Our youngest is 16 months and it does seem like overalls are less common now.
Our absolute favorite piece of clothing from our first child (he's 14 yrs now) was his pair of 18 month size Baby Gap denim overalls. They fit great, the straps didn't fall down, they were comfortable, and after 5 kids, they are still in perfect shape.
About a month ago, I put them on our youngest, but he didn't like them. He kept pulling on the straps and trying to get them off. I realized that this was the first time he'd had overalls on because these are the only one's we still had.