Because each zoom level is rendered individually. Some are rendered more often, some less often. Some are cached pre-rendered and some get rendered on-demand. And of course your local browser cache also matters, you should try to clear it. For a more detailed answer see the two following questions: - [How often does the main (mapnik) map get updated?][1] - [I have made edits but they don't show up on the map][2] [1]: https://help.openstreetmap.org/questions/178/how-often-does-the-main-mapnik-map-get-updated [2]: https://help.openstreetmap.org/questions/102/i-have-made-edits-but-they-dont-show-up-on-the-map

Because each zoom level is rendered individually. Some are rendered more often, some less often. Some are cached and some get rendered on-demand. And of course your local browser cache also matters, you should try to clear it. For a more detailed answer see the two following questions: - [How often does the main (mapnik) map get updated?][1] - [I have made edits but they don't show up on the map][2] [1]: https://help.openstreetmap.org/questions/178/how-often-does-the-main-mapnik-map-get-updated [2]: https://help.openstreetmap.org/questions/102/i-have-made-edits-but-they-dont-show-up-on-the-map

Because each zoom level is rendered individually. Some are rendered more often, some less often. Some are cached and some get rendered on-demand. For a more detailed answer see the two following questions: - [How often does the main (mapnik) map get updated?][1] - [I have made edits but they don't show up on the map][2] [1]: https://help.openstreetmap.org/questions/178/how-often-does-the-main-mapnik-map-get-updated [2]: https://help.openstreetmap.org/questions/102/i-have-made-edits-but-they-dont-show-up-on-the-map