Super Mario Bros. 3: The Forgotten 1-up Guide: Part 1
by jdaster12.8

This guide mentions 39 1-ups in Super Mario Bros. 3 + Super Mario Advance 4 that are easily forgotten. Locations with an asterisk * are 1-ups only found in Super Mario Advance 4.
The number following a location is the degree of frequency (1-5) to which it is forgotten (or else not known).

1. At the end of the bonus coin airship, jump above the space between the first two windows to reveal an invisible block. (5)

2. Jump above the right side of the secret pipe in 1-2. This one is past the top of the screen. (3)

3-4. High in the air, above the beginning of the fourth chain of coins in Coin Heaven, 1-3 and 1-5 only. (2)

5. To the left of the fourth set of three coins in 2-2. (1)

6. In the pyramid's secret area, jump around above the top row of blocks to find a 1-up past the top of the screen. (4)

7. At the very end of 3-2, after you enter the pipe, fly over the exit pipe to find a small platform on a track. Jump above the left end of the track to find a hidden 1-up block. (5)

8. On a small island far past the exit pipe in 3-3 --- EXTREMELY HARD TO GET. (5)

Continued in part 2 coming soon...