I thought it would be interesting to see what Dallas would look like if it hadn't expanded to 342.5 sq. mi. but instead had stayed "in the pack" with the likes of Atlanta, Denver, Detroit, Philadelphia, Portland, etc. In 2000, Dallas had a population of 1,188,580 in 342.54 sq. mi. That made it one of the biggest cities in regards to municipal population as well as land area. However, Dallas' municipal boundaries are 2x to 3x larger than most of its peers.
For example,
Philadelphia - 1,517,550 - 135.09 sq. mi.
Detroit - 951,270 - 138.77 sq. mi.
San Jose - 894,943 - 174.86 sq. mi.
Denver - 554,636 - 153.35 sq. mi.
Portland - 529,121 - 134.32 sq. mi.
Atlanta - 416,474 - 131.75 sq. mi.
So, how "big" would Dallas be if it were more comparable to the other cities? Using Census Tracts and sticking with those that are currently within the city limits, Dallas had a population of 616,690 in 140.30 sq. mi.
Here's a map showing the imaginary boundaries:
It should be interesting to see how much the population has risen since 2000 within these particular boundaries.