Joshua Tree just opened, before a three-day weekend. Here’s what to expect

This park’s reopening has set off a race to the desert among hundreds of hikers, climbers and adventure-starved families rushing to grab up the park’s 520 camping spots before the temperature climbs in coming days. Rangers say this influx, which began with Sunday’s low-profile reopening and picked up steam Tuesday and Wednesday, is manageable so far. But it may be the beginning of a hot, busy, …