| USPTO class | count (USPTO class) | USPTO Description |
| 123 | 150 | Internal-combustion engines |
| 166 | 102 | Wells |
| 424 | 83 | Drug, bio-affecting and body treating compositions |
| 210 | 50 | Liquid purification or separation |
| 60 | 48 | Power plants |
| 524 | 41 | Synthetic resins or natural rubbers -- part of the class 520 series |
| 426 | 38 | Food or edible material: processes, compositions, and products |
| 417 | 35 | Pumps |
| 508 | 29 | Solid anti-friction devices, materials therefor, lubricant or separant compositi |
| 106 | 28 | Compositions: coating or plastic |
| 384 | 28 | Bearings |
| 208 | 26 | Mineral oils: processes and products |
| 73 | 26 | Measuring and testing |
| 525 | 25 | Synthetic resins or natural rubbers -- part of the class 520 series |
| 62 | 22 | Refrigeration |
| 428 | 20 | Stock material or miscellaneous articles |
| 184 | 18 | Lubrication |
| 554 | 18 | Organic compounds -- part of the class 532-570 series |
| 175 | 17 | Boring or penetrating the earth |
| 418 | 16 | Rotary expansible chamber devices |
| 514 | 16 | Drug, bio-affecting and body treating compositions |
| 507 | 16 | Earth boring, well treating, and oil field chemistry |
| 180 | 15 | Motor vehicles |
| 474 | 15 | Endless belt power transmission systems or components |
| 137 | 13 | Fluid handling |
| 165 | 13 | Heat exchange |
| 475 | 13 | Planetary gear transmission systems or components |
| 29 | 13 | Metal working |
| 192 | 12 | Clutches and power-stop control |
| 324 | 11 | Electricity: measuring and testing |
| 188 | 11 | Brakes |
| 510 | 10 | Cleaning compositions for solid surfaces, auxiliary compositions therefor, or pr |
| 405 | 10 | Hydraulic and earth engineering |
| 252 | 9 | Compositions |
| 141 | 9 | Fluent material handling, with receiver or receiver coacting means |
| 701 | 9 | Data processing: vehicles, navigation, and relative location |
| 92 | 8 | Expansible chamber devices |
| 250 | 8 | Radiant energy |
| 526 | 8 | Synthetic resins or natural rubbers -- part of the class 520 series |
| 277 | 8 | Seal for a joint or juncture |
| 219 | 8 | Electric heating |
| 264 | 8 | Plastic and nonmetallic article shaping or treating: processes |
| 96 | 8 | Gas separation: apparatus |
| 430 | 8 | Radiation imagery chemistry: process, composition, or product thereof |
| 44 | 7 | Fuel and related compositions |
| 502 | 7 | Catalyst, solid sorbent, or support therefor: product or process of making |
| 516 | 7 | Colloid systems and wetting agents; subcombinations thereof; processes of |
| 702 | 7 | Data processing: measuring, calibrating, or testing |
| 523 | 7 | Synthetic resins or natural rubbers -- part of the class 520 series |
| 477 | 7 | Interrelated power delivery controls, including engine control |
| 435 | 6 | Chemistry: molecular biology and microbiology |
| 440 | 6 | Marine propulsion |
| 423 | 6 | Chemistry of inorganic compounds |
| 99 | 6 | Foods and beverages: apparatus |
| 356 | 6 | Optics: measuring and testing |
| 239 | 6 | Fluid sprinkling, spraying, and diffusing |
| 562 | 6 | Organic compounds -- part of the class 532-570 series |
| 585 | 6 | Chemistry of hydrocarbon compounds |
| 95 | 5 | Gas separation: processes |
| 114 | 5 | Ships |
| 528 | 5 | Synthetic resins or natural rubbers -- part of the class 520 series |
| 251 | 5 | Valves and valve actuation |
| 476 | 5 | Friction gear transmission systems or components |
| 800 | 5 | Multicellular living organisms and unmodified parts thereof and related processe |
| 280 | 5 | Land vehicles |
| 451 | 5 | Abrading |
| 310 | 5 | Electrical generator or motor structure |
| 241 | 5 | Solid material comminution or disintegration |
| 385 | 5 | Optical waveguides |
| 422 | 5 | Chemical apparatus and process disinfecting, deodorizing, preserving, or sterili |
| 359 | 5 | Optical: systems and elements |
| 164 | 4 | Metal founding |
| 436 | 4 | Chemistry: analytical and immunological testing |
| 81 | 4 | Tools |
| 138 | 4 | Pipes and tubular conduits |
| 173 | 4 | Tool driving or impacting |
| 174 | 4 | Electricity: conductors and insulators |
| 703 | 4 | Data processing: structural design, modeling, simulation, and emulation |
| 37 | 4 | Excavating |
| 530 | 4 | Chemistry: natural resins or derivatives; peptides or proteins; lignins or react |
| 340 | 4 | Communications: electrical |
| 144 | 4 | Woodworking |
| 427 | 4 | Coating processes |
| 220 | 4 | Receptacles |
| 74 | 4 | Machine element or mechanism |
| 399 | 4 | Electrophotography |
| PLT | 4 | Plants |
| 134 | 4 | Cleaning and liquid contact with solids |
| 148 | 4 | Metal treatment |
| 568 | 4 | Organic compounds -- part of the class 532-570 series |
| 91 | 3 | Motors: expansible chamber type |
| 372 | 3 | Coherent light generators |
| 16 | 3 | Miscellaneous hardware |
| 152 | 3 | Resilient tires and wheels |
| 415 | 3 | Rotary kinetic fluid motors or pumps |
| 429 | 3 | Chemistry: electrical current producing apparatus, product, and process |
| 521 | 3 | Synthetic resins or natural rubbers -- part of the class 520 series |
| 366 | 3 | Agitating |
| 401 | 3 | Coating implements with material supply |
| 257 | 3 | Active solid-state devices (e.g., transistors, solid-state diodes) |
| 414 | 3 | Material or article handling |
| 75 | 3 | Specialized metallurgical processes, compositions for use therein, consolidated |
| 72 | 3 | Metal deforming |
| 55 | 3 | Gas separation |
| 254 | 3 | Implements or apparatus for applying pushing or pulling force |
| 269 | 3 | Work holders |
| 202 | 3 | Distillation: apparatus |
| 374 | 2 | Thermal measuring and testing |
| 425 | 2 | Plastic article or earthenware shaping or treating: apparatus |
| 8 | 2 | Bleaching and dyeing; fluid treatment and chemical modification of textiles and |
| 536 | 2 | Organic compounds -- part of the class 532-570 series |
| 285 | 2 | Pipe joints or couplings |
| 431 | 2 | Combustion |
| 299 | 2 | Mining or in situ disintegration of hard material |
| 623 | 2 | Prosthesis (i.e., artificial body members), parts thereof, or aids and accessori |
| 512 | 2 | Perfume compositions |
| 169 | 2 | Fire extinguishers |
| 128 | 2 | Surgery |
| 222 | 2 | Dispensing |
| 416 | 2 | Fluid reaction surfaces (i.e., impellers) |
| 700 | 2 | Data processing: generic control systems or specific applications |
| 118 | 2 | Coating apparatus |
| 442 | 2 | Fabric (woven, knitted, or nonwoven textile or cloth, etc.) |
| 82 | 2 | Turning |
| 303 | 2 | Fluid-pressure and analogous brake systems |
| 33 | 2 | Geometrical instruments |
| 473 | 2 | Games using tangible projectile |
| 307 | 1 | Electrical transmission or interconnection systems |
| 162 | 1 | Paper making and fiber liberation |
| 108 | 1 | Horizontally supported planar surfaces |
| 203 | 1 | Distillation: processes, separatory |
| 438 | 1 | Semiconductor device manufacturing: process |
| 494 | 1 | Imperforate bowl: centrifugal separators |
| 552 | 1 | Organic compounds -- part of the class 532-570 series |
| 204 | 1 | Chemistry: electrical and wave energy |
| 392 | 1 | Electric resistance heating devices |
| 87 | 1 | Textiles: braiding, netting, and lace making |
| 119 | 1 | Animal husbandry |
| 261 | 1 | Gas and liquid contact apparatus |
| 604 | 1 | Surgery |
| 156 | 1 | Adhesive bonding and miscellaneous chemical manufacture |
| 34 | 1 | Drying and gas or vapor contact with solids |
| 53 | 1 | Package making |
| 101 | 1 | Printing |
| 439 | 1 | Electrical connectors |
| 342 | 1 | Communications: directive radio wave systems and devices (e.g., radar, radio nav |
| 351 | 1 | Optics: eye examining, vision testing and correcting |
| 14 | 1 | Bridges |
| 518 | 1 | Chemistry: fischer-tropsch processes; or purification or recovery of products th |
| 315 | 1 | Electric lamp and discharge devices: systems |
| 110 | 1 | Furnaces |
| 504 | 1 | Plant protecting and regulating compositions |
| 522 | 1 | Synthetic resins or natural rubbers -- part of the class 520 series |
| 100 | 1 | Presses |
| 209 | 1 | Classifying, separating, and assorting solids |
| 131 | 1 | Tobacco |
| 181 | 1 | Acoustics |
| 363 | 1 | Electric power conversion systems |
| 47 | 1 | Plant husbandry |
| 196 | 1 | Mineral oils: apparatus |
| 200 | 1 | Electricity: circuit makers and breakers |
| 140 | 1 | Wireworking |
| 347 | 1 | Incremental printing of symbolic information |
| 336 | 1 | Inductor devices |
| 600 | 1 | Surgery |
| 601 | 1 | Surgery: kinesitherapy |
| 312 | 1 | Supports: cabinet structure |
| 290 | 1 | Prime-mover dynamo plants |
| 382 | 1 | Image analysis |
| 4 | 1 | Baths, closets, sinks, and spittoons |
| 71 | 1 | Chemistry: fertilizers |
| 406 | 1 | Conveyors: fluid current |
| 341 | 1 | Coded data generation or conversion |
| 360 | 1 | Dynamic magnetic information storage or retrieval |
| 434 | 1 | Education and demonstration |
| 445 | 1 | Electric lamp or space discharge component or device manufacturing |
| 343 | 1 | Communications: radio wave antennas |
| 705 | 1 | Data processing: financial, business practice, management, or cost/price determi |
| 713 | 1 | Electrical computers and digital processing systems: support |
| 403 | 1 | Joints and connections |
| 441 | 1 | Buoys, rafts, and aquatic devices |
| 201 | 1 | Distillation: processes, thermolytic |
| 15 | 1 | Brushing, scrubbing, and general cleaning |
| 236 | 1 | Automatic temperature and humidity regulation |
| 43 | 1 | Fishing, trapping, and vermin destroying |
| 556 | 1 | Organic compounds -- part of the class 532-570 series |
| 211 | 1 | Supports: racks |
| 244 | 1 | Aeronautics and astronautics |
| 83 | 1 | Cutting |
| 187 | 1 | Elevator, industrial lift truck, or stationary lift for vehicle |
| 409 | 1 | Gear cutting, milling, or planing |
| 56 | 1 | Harvesters |
| 267 | 1 | Spring devices |