Round each population to the nearest thousand:<br>
&bull; 328,499 → 328,000 (hundreds digit 4 < 5)<br>
&bull; 672,501 → 673,000 (hundreds digit 5 &ge; 5)<br><br>
Estimated total = 328,000 + 673,000 = 1,001,000<br><br>
Final Answer: 1,001,000