BASE jumping has always been a fringe sport to some extent. This due to the danger, the fact that many "traditional" skydivers feel it gives their sport a bad image, and because jumping off of building, towers and bridges is against the law in most places. Even if the jump itself weren't illegal, gaining access to prime jumping spots often involves trespassing on private property, picking locks, climbing fences or deceiving security guards.
The National Park Service frowned upon the first few BASE jumps from El Capitan. Parachuting in national parks was prohibited at the time. For a short time, officials at Yosemite National Park allowed jumpers to apply for permits and jump from El Capitan legally. However, after a few months, they decided that jumpers were not following the rules and were causing environmental damage, and they have forbidden jumps ever since. Today, if you are caught BASE jumping in a national park in the United States, you face up to $2,000 in fines, and the cost of any rescue operations that may be necessary. Park authorities can confiscate all parachuting equipment, as well [ref].
BASE jumping from buildings within cities is almost always illegal. The risk of pedestrian injury and traffic disruption are too great, although the vast majority of building jumps take place at night or at dawn. Police have promptly arrest jumpers who have leapt from the Eiffel Tower and the St. Louis Arch.
There are quite a few places to BASE jump legally. Kjerag, on Lysefjord in Norway is a very popular location, and jumps remain legal there [ref]. Various natural formations throughout Europe are available for legal jumping as well. However, man-made objects with legal jumping are difficult to find, so anyone with a BASE number has probably had to break a law to get it. Bridge Day is the one obvious exception.
The specific locations of BASE jumping spots, whether legal or illegal, are closely guarded by BASE jumpers. There are several reasons for this. One is that many BASE jumpers want their sport to maintain a secretive and "outlaw" nature. Publicizing BASE jumping, or letting too many people into the sport, makes it harder to perform illegal jumps because authorities will be on guard. One of the worst things a BASE jumper can do is something that will make jumps more difficult for other jumpers. This includes getting arrested, getting killed or injured or otherwise drawing attention to the illegal side of BASE. BASE jumpers broke into the apartment of a jumper who was arrested attempting a daylight jump in Atlanta and beat him for retribution [ref].
The secretive nature of BASE jumping means that many of the statistics about the sport have to be taken with a grain of salt. No one keeps exact records on the many jumps (and deaths or injuries) that happen at night, in the wilderness or with no one else around. However, the current BASE number is above 1,000, and the World BASE Fatality List reached 97 on May 6, 2006. The highest BASE jump was probably a jump off Pakistan's Trango Towers in 1992. Two jumpers successfully leapt off a cliff over 19,000 feet high [ref]. That's about 4,000 feet higher than most skydiving planes go. The lowest feasible jump is anything around 250 feet, although using a static line with a short length, a jump could be accomplished with a full parachute deployment from much lower -- it just wouldn't be much of a jump. Finally, the first person to jump all four BASE types was Phil Smith. He will always be BASE #1.
For lots more information on BASE jumping and related topics, check out the links on the next page.