In the last 90 days, 1 listings have been made available, which means new listings most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 900% of the available space in the Brownsville are subleases, so you might be able to find a shorter term or below market rent. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around sqft. Most buildings in this region are around 1 stories. Most buildings in this market were built in 1990 and are Class A.