A border checkpoint is a location on an international border where travelers or goods are inspected and allowed (or denied) passage through. Authorization often is required to enter a country through its borders. Access-controlled borders often have a limited number of checkpoints where they can be crossed without legal sanctions. Arrangements or treaties may be formed to allow or mandate less restrained crossings (e.g. the Schengen Agreement). Land border checkpoints (land ports of entry) can be contrasted with the customs and immigration facilities at seaports, international airports, and other ports of entry.
Checkpoints generally serve two purposes:
In some countries (e.g. China) there are border checkpoints for both those entering and those exiting the country, while in others (e.g. U.S. and Canada), there are border checkpoints only when entering the country. (There are also United States Border Patrol interior checkpoints.)
The Schengen Borders Code, which forms part of the law of the European Union, defines some terms as follows (particularities with respect to the EU are left out, in order to emphasize general usability of those definitions): 
These definitions mean that a place where a road crosses an internal Schengen border is legally not a "border crossing point".
This is a list of the busiest land border checkpoints in the world, handling more than 35 million travelers in both directions annually. These travelers (or individual crossings) comprise pedestrians, drivers and vehicle passengers. International border checkpoints are in green.
|Rank||Border checkpoints||Annual Travelers||Notes|
|1||Gongbei Port||China||Macau||Posto Fronteiriço das Portas do Cerco||134,000,000||(2018) |
|2||Sultan Iskandar Building||Malaysia||Singapore||Woodlands Checkpoint||127,750,000||(2012)  [Note 1]|
|3||Luohu Port||China||Hong Kong||Lo Wu Control Point||81,707,959||(2017) |
|4||Puerto Fronterizo El Chaparral||Mexico||United States of America||San Ysidro Port of Entry||69,300,000||(2018)  [Note 2]|
|5||Futian Port||China||Hong Kong||Lok Ma Chau Spur Line Control Point||59,464,480||(2017) |
|6||Shenzhen Bay Port||China||Hong Kong||Shenzhen Bay Control Point||45,118,797||(2017) |
|7||Huanggang Port||China||Hong Kong||Lok Ma Chau Control Point||37,059,848||(2017) |
|8||Puerto Fronterizo Mesa de Otay||Mexico||United States of America||Otay Mesa Port of Entry||35,400,000||(2018)  [Note 2]|
This is a list of the busiest airports in the world, by international passenger traffic, as of 2018. Airports serving international passengers are effectively checkpoints, and have the proper customs, immigration and quarantine facilities. Airports Council International's (January–December) preliminary figures are as follows. 
|1||Dubai International Airport||United Arab Emirates||88,885,367|
|2||London Heathrow Airport||United Kingdom||75,306,939|
|3||Hong Kong International Airport||Hong Kong||74,360,976|
|4||Amsterdam Airport Schiphol||Netherlands||70,956,258 [Note 3]|
|5||Seoul Incheon International Airport||South Korea||67,676,147|
|6||Paris-Charles de Gaulle Airport||France||66,383,494 [Note 3]|
|7||Singapore Changi Airport||Singapore||64,890,000|
|8||Frankfurt Airport||Germany||61,774,663 [Note 3]|
|10||Atatürk International Airport||Turkey||48,978,770|
This is a list of the busiest seaports in the world, with proper customs, immigration and quarantine facilities to be deemed as maritime checkpoints. Although figures simply represent total passenger traffic, most (if not, all) of the passengers served at these ports are bound for other countries and have to pass through checkpoint (i.e. the port is not a domestic one). This list only includes ports that handle more than 4 million passengers annually.
|1||Taipa Ferry Terminal||Macau||24,000,000||(2017)  [Note 4]|
|2||Hong Kong–Macau Ferry Terminal||Hong Kong||17,317,037||(2017) |
|3||Outer Harbour Ferry Terminal||Macau||15,000,000||(2013) |
|4||Port of Helsinki||Finland||12,300,000||(2017)  [Note 3]|
|5||Port of Dover||United Kingdom||11,700,000||(2017) |
|6||Hong Kong-China Ferry Terminal||Hong Kong||7,074,940||(2017) |
|8||Port Canaveral||USA||4,500,000||(2016) |
United States–Mexico border checkpoint at Nogales, Arizona.
Old border post on the France–Spain border (both countries now part of the Schengen Area)
Looking into Austria from Liechtenstein, with a joint border station. Since Liechtenstein joined the Schengen Area in 2011, this border station is for customs formalities only.
Nekhoteevka customs on the Russia–Ukraine border.
Posto Fronteiriço das Portas do Cerco on the Macanese side of the Zhuhai–Macau border.