Select the Correct Sign: Comparing 240,990 and 240,909

To solve this problem, we'll follow these steps:

• Step 1: Compare the digits of both numbers from left to right.
• Step 2: Identify where the first differing digit occurs and determine which number is greater based on this difference.

Now, let's work through each step:
Step 1: Begin by comparing each digit of $240,990$ and $240,909$ from left to right.
- Both numbers share the digits 2, 4, and 0 in the hundred-thousands, ten-thousands, and thousands places, respectively.
Step 2: Next, the hundreds digits are compared. Here, $240,990$ has a 9, whereas $240,909$ has a 0.
- Since 9 is greater than 0, $240,990$ is the larger number.

Therefore, the sign that correctly compares $240,990$ and $240,909$ is $\boxed{>}$.

Concluding the solution, $240,990 > 240,909$.