100 Pesos 180th Anniversary of the Union of States (2004): Value Guide

If you inherited or found a Mexican 100 Pesos coin marked "180 Aniversario de la Unión de los Estados" from 2004, here is the honest answer: it is a bimetallic commemorative with a silver center, worth from a few dollars up into the low hundreds depending on condition and whether it still has its original case. It is not a rare coin worth thousands, but it is not junk either.

This piece is part of a Mexican state series (Tamaulipas edition, proof finish) issued by Banxico, the Mexican central bank, in 2004 only. That single-year issue is genuinely collectible, but it was made for collectors, not general circulation, so most examples have survived in good shape.

What this coin actually is

The "100 Pesos 180 Aniversario" is a bimetallic commemorative: a precious-metal center ring surrounded by an outer ring of base alloy. It was struck in proof finish, meaning mirror-like fields and frosted raised details, the finish reserved for collector coins sold in individual cases (yours may be numbered, for example "No. Pza. A 0241").

Here are the verified specifications. Check yours against these first:

Spec	Value
Face value	100 Pesos
Year	2004 (single year of issue)
Weight	29.17 grams
Diameter	34.5 mm
Composition	Bimetallic (silver center, base-metal ring)
Edge	Plain
Finish	Proof
Series	Union of the States / state commemoratives

The "100 Pesos" printed on the coin is its face value in Mexican pesos, not its collector value and not a dollar amount.

What it is worth in USD

Value on these bimetallic commemoratives is driven by three things: condition (grade), whether it still has the original Banxico case and certificate, and the silver in the center ring.

• Circulated, no case, visible wear: roughly 8 to 25 USD. At this level you are close to the value of the silver plus a small collector premium.
• Uncirculated, no case: roughly 25 to 60 USD.
• Proof with original numbered case and certificate: roughly 60 to 200 USD, sometimes more for a pristine, professionally graded example.

Anyone telling you a single 2004 100 Pesos commemorative is worth thousands of dollars is inflating it. The realistic ceiling for a standard example in top condition with its packaging sits in the low hundreds. If you want the exact figure for yours, grade and packaging decide it, so read the grading section below.

Is it rare?

Not in the classic sense. Banxico did not publish a hard mintage figure for this specific case-issued piece, which usually means it came out in a restricted numismatic set rather than in the millions. Limited, yes. Rare enough to command a fortune, no. Because it was sold to collectors in cases, plenty of clean examples exist, and that keeps prices grounded. Its appeal is being a single-year commemorative from a defined state series, not extreme scarcity.

How to tell if yours is genuine

Start with a scale and a caliper. A real example weighs 29.17 grams and measures 34.5 mm across. If your coin is off on either number, stop there.

Next, look at the relief. Genuine proof strikes have sharp, frosted raised details against mirror fields. Counterfeits and fakes tend to look flat, soft, and dull. Compare against official Banxico images.

For a piece you plan to insure or sell above roughly 100 USD, professional certification from NGC or PCGS is the definitive answer. They authenticate and assign a grade, which also raises what a buyer will pay. See our coin grading and condition guide to understand what those grades mean before you spend money on it.

Errors and varieties

Genuine mint errors (off-center strikes, die rotation, doubled dies) can multiply value if verified. Be skeptical: most "errors" people post online are post-mint damage such as scratches, corrosion, or knocks, not factory errors. If you think you have a real one, get it looked at before you get excited. You can post clear photos in the Pesoteca forum for a second opinion.

Where to sell it

Do not dump it on the first Facebook offer. Your realistic options:

• A verified numismatic shop from the Pesoteca directory: they appraise on the spot and pay fair prices.
• The Pesoteca buy-and-sell forum, where you deal directly with collectors who know the series.
• Established coin dealers and numismatic fairs, worth it for anything above roughly 100 USD because they can authenticate.

Before you sell, photograph the obverse, reverse, and edge in good light, note the weight, and confirm the price range above. If your coin still has its numbered case and certificate, keep them together, they add real money.

Have the 2004 100 Pesos coin sitting in a drawer and not sure which state edition you have? Post your photos in the Pesoteca forum and we will help you identify it and estimate a fair price.