Plain-language explanations of the spatial systems, administrative datasets and formulas behind Open Map Lab's tools. Each post lists the primary sources it relies on.
The Mercator projection is a cylindrical map projection that keeps angles and local shapes correct by stretching the map more and more toward the poles. That stretch is why Greenland, about one fourteenth the size of Africa, looks just as large on most world maps and on the web maps in your phone.
The fastest way to find out what county you live in is to look up your exact location or street address against county boundaries, not your ZIP code. This guide compares the methods (GPS, address lookup, the Census Bureau geocoder and official records), explains why ZIP codes and mailing cities mislead, and covers county equivalents and addresses near a county line.
A ZCTA (ZIP Code Tabulation Area) is the Census Bureau’s polygon version of a ZIP code, built from census blocks so that statistics can be mapped by ZIP. The Postal Service itself assigns ZIP codes to delivery routes and post offices and publishes no boundaries. This guide explains how ZIP codes are assigned, how ZCTAs are built, where the two disagree and which one to use for a given job.
When you click "Find My Location" in a browser, the device chooses among satellite positioning (GPS, Galileo and other GNSS), Wi-Fi positioning, cell towers and, as a last resort, IP address geolocation. Which one answers explains why accuracy can range from a few meters to many miles. This guide explains each method, what the accuracy number means, what degrades it, and how to get a better fix before relying on a location-based lookup.
In pure geometry, Earth turns 15 degrees of longitude every hour, so 24 neat stripes would make sense. In reality time zones are political and commercial boundaries set by law, bent around cities, counties and countries. This guide explains who sets U.S. time zone boundaries, why they wander, how daylight saving time and IANA zone IDs fit in, how this site determines your zone, and the mistakes that most often cause missed meetings.
Sea level, as used for elevations, is mean sea level: the average height of the ocean surface measured at tide stations over a 19-year epoch, extended under the land as the geoid. This guide explains tidal datums, the difference between elevation and altitude, why GPS height is measured from a different surface, how elevation models such as Copernicus GLO-90 work, and why different sources disagree.
Latitude tells you how far north or south of the Equator a place is (0° to 90°), and longitude tells you how far east or west of the Prime Meridian it is (0° to 180°). This guide compares the two side by side, shows how to read coordinates in decimal and degrees-minutes-seconds form and off a map, gives memory tricks, and explains precision, sign conventions and datums.
"As the crow flies" means the straight-line distance between two places: the shortest path over Earth's curved surface, ignoring roads. Driving distance follows the road network around rivers, mountains and one-way streets. This guide explains how geodesic distance is computed, how to calculate and interpret the detour factor, how this site estimates road distance, and why contracts and tax rules care which one you use.
The same spot on Earth can be written as decimal degrees (DD), degrees-minutes-seconds (DMS), degrees and decimal minutes (DMM), UTM or MGRS. This guide shows how to recognize each format at a glance, converts one real location through all of them by hand, explains how UTM eastings and northings are built, and lists the mistakes that most often send a point to the wrong place.
California is the most populous state with 39,355,309 residents on July 1, 2025, and Wyoming is the least populous with 588,753, according to the Census Bureau's Vintage 2025 estimates. This list ranks all 50 states and DC with change since the 2020 Census, share of the national total and population density.
In the United States, daylight saving time 2026 began at 2:00 a.m. on Sunday, March 8 and ended at 2:00 a.m. on Sunday, November 1; the next change is March 14, 2027. This guide gives the dates through 2030 computed from the federal rule, lists the places that never change their clocks, explains where the Sunshine Protection Act stands, and shows the weeks when the US and Europe are out of step.
The Earth is 24,901 miles (40,075 km) around at the Equator and 24,860 miles (40,008 km) around through the poles, because it bulges slightly at the Equator. This guide shows where those numbers come from, the radius and diameter, how Eratosthenes measured the planet around 240 BCE, and how long a trip around it takes.
The 50 states use six standard time zones, and federal law defines nine once Puerto Rico, the U.S. Virgin Islands, American Samoa, Guam and the Northern Mariana Islands are included. This guide lists every zone with its offsets, maps them, explains which 14 states are split between two zones, and sorts out why some sites say four, eleven or twelve.
Alaska is the largest U.S. state at 665,725 square miles of total area, and Rhode Island is the smallest at 1,545 square miles. This guide ranks all 50 states by total, land and water area using the Census Bureau's 2026 Gazetteer, and sets each against its population rank.
Arizona, Colorado, New Mexico and Utah are the Four Corners states, and the Four Corners Monument is the only place in the United States where four states touch. This post maps the corner, explains how 19th-century surveyors placed it, and shows why the claim that the monument is 2.5 miles off comes from using the wrong prime meridian.
On a computer, right-click any spot in Google Maps and the latitude and longitude appear at the top of the menu; click them to copy. On a phone, touch and hold the map to drop a pin and read the coordinates from the search box or the place sheet. This guide covers each platform, the formats Google accepts when you paste coordinates back in, and the mistakes that put pins in the wrong hemisphere.
There are 3,144 counties and county equivalents in the 50 states and the District of Columbia, according to the Census Bureau's 2026 Gazetteer. Texas has the most (254) and Delaware the fewest (3); this guide lists every state's count and explains parishes, boroughs, independent cities and Connecticut's planning regions.
A map projection is the mathematical rule that turns latitude and longitude on the curved Earth into x and y on a flat map, and every projection distorts area, shape, distance or direction somewhere. This guide explains the three families, the four properties a projection can keep, compares the projections you actually meet, and shows how to pick one.
Denali (Mount McKinley) in Alaska is the highest point of any state at 20,310 feet, and Florida's Britton Hill is the lowest state high point at 345 feet. This table lists every state's highest and lowest point from USGS data, with notes on why published elevations differ by a few feet.
Four states border Mexico (Texas, Arizona, New Mexico and California) and thirteen border Canada, from Alaska to Maine. This post lists both with official border lengths, the Mexican states and Canadian provinces across the line, and explains why published totals disagree.
For an adult standing at the water's edge, the horizon is about 3 miles (5 km) away, and the distance grows with the square root of eye height. This guide gives the formula in miles and kilometers, a computed table from beach level to a jet at 35,000 feet, the effect of atmospheric refraction, and how to tell whether a distant ship, island or tower should be visible.
Google Maps has no elevation readout for a clicked point. Its Terrain layer draws contour lines with gray height labels in hilly areas, Google Earth Pro reports the elevation under the cursor and draws profiles along a path, and cycling directions can show the climb on a route. This guide covers each method, how to read contour lines, their limits, and quicker ways to look up the elevation of any point.
The largest county in the United States is San Bernardino County, California, with 20,068 square miles of land, unless you count Alaska's county equivalents, in which case Yukon-Koyukuk Census Area (145,768 sq mi) is seven times larger. This guide ranks the largest, smallest and most populous counties from Census Bureau data.
The United States has three widely quoted centers: near Lebanon, Kansas, for the contiguous 48 states, north of Belle Fourche, South Dakota, for all 50 states, and in Wright County, Missouri, for the 2020 population. This post explains where each is, how it was calculated, and why our own recalculation lands within about 20 miles of the official figures.
A census designated place (CDP) is a named community without its own municipal government that the Census Bureau defines so it can publish statistics for it. This post explains how CDPs differ from incorporated places, unincorporated areas and townships, lists the largest CDPs, and covers what living in one means for taxes, services and your mailing address.
Our posts cite official statutes (U.S. Code, CFR), federal geospatial standards (USGS, Census Bureau, NGS), and primary geodetic research (Charles Karney, Jean Meeus). See the editorial policy.
