- Have John Maynard Keynes and Gunnar Myrdall never pursue careers in economics.
- Keep the Gold Standard.
- Roosevelt assassinated, so no New Deal in the US. Give Calvin Coolidge better health, so he can run in 1928 (and yes, he'd be far worse than Hoover).
- Hitler dies in World War One, so the world economy is never rescued via increased military spending.
- In terms of pre-1900 PODs, find a way of eliminating Bernstein-style Revisionist Marxism. If you keep Social Democracy overtly "revolutionary", you're much more likely to keep Classical Liberals in office until the entire political edifice goes under.