Scroll to the widest strip on almost any county band plan and you are looking at the result of a single sale. FCC Auction 107 closed in early 2021 with gross bids of about $81 billion, the most ever raised for spectrum in the United States. It sold 280 MHz between 3.7 and 3.98 GHz, cleared of the satellite services that used to live there.
Who bought what
Verizon bid roughly $45 billion and came away with the largest position, between 140 and 200 MHz depending on the market. AT&T bid about $23 billion for 80 MHz in most markets. T-Mobile, which already held a deep 2.5 GHz position from its merger with Sprint, bid about $9 billion for an average of 40 MHz in the larger markets.
The band is divided into fourteen 20 MHz blocks. The first five, the A blocks, were cleared early in 46 large markets and went into service at the start of 2022. The rest followed at the end of 2023.
Why it reads as one band with its neighbour
Below C-band sits the 3.45 GHz band, sold in the auction that followed, and between them the shared CBRS band. Phones treat 3.45 GHz and C-band as a single 5G band, n77. That is why carrierdepth draws them on one strip: a carrier with licences on both sides of CBRS can combine them, and you can see at a glance who can.
What it means on a county page
Three patterns show up again and again.
- Verizon's high-band total is mostly C-band. Without it, Verizon would have little spectrum between 2.3 and 6 GHz.
- AT&T's is split between C-band and 3.45 GHz, which it bought heavily in the following auction.
- T-Mobile's is mostly 2.5 GHz (n41), a band it largely had to itself and deployed years before C-band was usable.
The totals can look similar. The band plans do not, and the difference matters: 2.5 GHz reaches a little further than 3.7 GHz from the same tower, and it was on the air first.
Check your own county
Holdings differ by market, sometimes sharply, because bidding was market by market and licences have been traded since. The national story is a guide; the county strip is the fact.
Auction figures are gross bids as reported in the FCC's Auction 107 closing public notice, rounded.